Forward-merge the src/nostr / src/mdns rendezvous reorganization
(relocation out of src/discovery/, the Discovery->Rendezvous rename, the
RendezvousDriver consolidation, and the trace-target reference updates)
onto the next branch. The sole conflict was in the LAN poll method's
doc-comment and signature: kept next's XX-handshake wording and applied
the lan_rendezvous rename. Merged tree builds clean; next lib suite 1583
passing, fmt/clippy clean.
Moving the nostr rendezvous engine to src/nostr/ (and mDNS to src/mdns/)
changed the module-path-derived tracing targets from
fips::discovery::nostr::* to fips::nostr::*. Update the RUST_LOG filters
in the NAT and mesh-lab test compose files and the resolve-peers-via-nostr
tutorial's debug recipe to the new targets so trace configs and the
documented journal-watch command keep emitting the intended lines.
Without this, the stun-faults suite's Phase-0 pre-flight (which greps the
daemon journal for the debug-level "STUN observation succeeded" /
"traversal: initiator STUN observed" lines) saw those lines suppressed —
the daemon behaved correctly, but the stale RUST_LOG target hid the
evidence. Test-harness and docs only; no source or behavior change.
Pull the rendezvous driver state and the movable driver logic out of the
Node struct into the src/nostr home. A new RendezvousDriver owns the
engine handle and the four bookkeeping fields (traversal start time,
startup-sweep latch, adopted bootstrap-transport set and their npubs)
that previously sat loose on Node; Node holds a single driver field and
reaches the same data through thin accessors, including the rx-loop
hot-path protocol-mismatch hook.
The advert build/refresh, the via_nostr fallback-address resolve, the
overlay-endpoint-to-PeerAddress mapping, and the bootstrap request move
onto the driver, taking their Node inputs explicitly (a transport-
endpoint snapshot for advert building) rather than reading Node fields
directly. Transport/connection-table-bound work (traversal adoption,
bootstrap-transport cleanup, the open-discovery sweep, and the outbound
budget calculators) stays on Node as thin glue that calls into the
driver.
Behavior-neutral relocation: statements moved verbatim, no logic, wire,
config-key, or metric changes. lifecycle.rs shrinks ~230 lines. cargo
fmt/build/clippy clean; lib suite 1547 passing (baseline unchanged).
Relocate the overlay peer-rendezvous subsystem out of the overloaded
src/discovery/ tree into two focused, independent homes: src/nostr/
(relay-mediated overlay endpoint advertise/resolve/auto-mesh plus NAT
traversal) and src/mdns/ (link-local DNS-SD rendezvous). The two
subsystems are independent, so they get separate homes rather than
sharing one.
Drop the ambiguous "Discovery" stem from their identifiers in favor of
"Rendezvous": NostrDiscovery -> NostrRendezvous, LanDiscovery ->
LanRendezvous, and the matching config, policy, field, and method names.
The former src/discovery.rs handoff types (EstablishedTraversal,
BootstrapHandoffResult, the punch-packet helpers) fold into
src/nostr/handoff and stay reachable via the crate-root re-exports.
Pure relocation and rename: no logic, wire-format, config-key, metric,
or tracing-target changes. The operator-facing node.rendezvous.nostr.*
and node.rendezvous.lan.* config keys and the fips-overlay-v1 advert
namespace are byte-identical. cargo fmt/build/clippy clean; lib test
suite 1547 passing (baseline unchanged).
Forward-merge the mesh-lookup "discovery" disambiguation onto the next
line: the lookup handler module and Node.lookup field renames, the lookup
metric types, the dual-emitted lookup/discovery metric family, and the
node.discovery -> node.lookup/node.rendezvous config split with its
deprecation shim.
Conflicts resolved by keeping next's XX handshake path (the inbound
responder stores pending_inbound for msg3 rather than promoting on msg1)
and renaming its reset_discovery_backoff call sites to reset_lookup_backoff;
the CHANGELOG Unreleased entries from both lines are combined.
The identifier "discovery" named three unrelated subsystems; the FMP
overlay coordinate-lookup subsystem is now consistently "lookup". This
finishes the concept-#1 rename across the shell, config, and metric
layers left after the earlier proto-layer rename:
- Handler module node::handlers::discovery -> node::handlers::lookup, and
reset_discovery_backoff -> reset_lookup_backoff.
- The Node lookup-engine field Node.discovery -> Node.lookup, renamed by
resolved binding so the metrics().discovery and node.discovery config
paths are left untouched.
- The lookup metric types DiscoveryMetrics -> LookupMetrics,
DiscoveryStatsSnapshot -> LookupStatsSnapshot, and Metrics.discovery ->
Metrics.lookup.
Two surfaces cross a stability boundary and ship behind a compatibility
window, both marked in-code for removal at the v2 cutover:
- The control-socket metric family is dual-emitted under both "discovery"
(deprecated alias) and "lookup" so existing dashboards keep working.
- The node.discovery.* config table is split into node.lookup.* (mesh
lookup scalars) and node.rendezvous.* (nostr/lan peer rendezvous).
NodeConfig does not deny unknown fields, so a naive rename would make a
deployed node.discovery: block deserialize into nothing and silently
revert every setting to default. A deprecated all-Option
DiscoveryConfigCompat field captures a legacy block and a new post-parse
Config::normalize_deprecated_keys pass folds it into the new tables with
a one-time deprecation warning.
Flip the packaged fips.yaml templates to the new keys, add legacy/new/
scalar compat parse tests, and record the split and deprecations in the
CHANGELOG. Behavior-neutral; fmt/clippy clean, lib suite green.
The previous portability fix bounded the powi test's drift from std::powi
at an absolute ULP count, but Windows/MSVC drift grows with the exponent
(3 ULP by exp=14), so no fixed ULP bound is portable.
Replace the ULP oracle with a loose relative-tolerance sanity sweep
(1e-11), which any sane libm clears by ~1000x regardless of exponent
while still catching a grossly wrong impl. Add a golden-bit pin for the
exp=14 case that exposed the growth. The powi function is unchanged; the
golden-bit determinism pins already passed on Windows.
The powi guard test asserted our square-and-multiply result was
bit-for-bit equal to f64::powi, which failed the Windows unit-test job by
one ULP. f64::powi is not portably bit-stable: Linux and macOS lower it
to compiler-rt's __powidf2, but Windows/MSVC rounds differently.
Our square-and-multiply is pure IEEE-754 f64 multiplication and is
therefore deterministic across every platform, which is the property that
actually matters for mesh nodes to agree on bloom FPR and backoff timing
regardless of OS. Replace the std bit-equality assertion with golden-bit
pins on our own output (locking that cross-platform determinism) plus a
bounded-drift sanity sweep against std::powi. The powi function itself is
unchanged.
Forward-merge the mesh discovery module rename (directory, exported types, and
internal lookup-stem terminology) onto the next wire-format line. next's
divergent lookup wire and core content is preserved under the new proto/lookup
path, with the same terminology sweep applied to its next-only lines.
Rename src/proto/discovery to src/proto/lookup and bring the module's naming
onto the lookup stem, matching its concept: a mesh lookup of a node's
coordinates from its pubkey, sent into the mesh as a bloom-filter-guided
multicast request that returns a unicast response with the coordinates.
- the module directory and its declaration (proto::discovery -> proto::lookup)
- exported types: DiscoveryAction -> LookupAction, DiscoveryBackoff ->
LookupBackoff, DiscoveryForwardRateLimiter -> LookupForwardRateLimiter,
MAX_RECENT_DISCOVERY_REQUESTS -> MAX_RECENT_LOOKUP_REQUESTS, and the Discovery
state struct -> Lookup
- internal terminology: doc comments, the "overlay-lookup" phrasing, the
empty_discovery/suppressing_discovery test helpers, and the disc
parameter/variable all take the lookup names
- the already-lookup-named wire types (LookupRequest/LookupResponse) are unchanged
Behavior-neutral: no wire bytes or decision logic change. Two references are
intentionally kept as "discovery": the still-named node::handlers::discovery
shell module and the node.discovery.* config keys, which belong to the broader
disambiguation of the shell, config, and metric surfaces still to come.
Bring the proto tree closer to a std+alloc-only posture, behavior unchanged on
every decision path:
- Sweep the remaining std::fmt and std::collections imports over to core::fmt
and alloc::collections across the wire codecs and their tests. Subsystem files
that shadow the core name with a child core module use the leading-colon
::core::fmt form. Imports only.
- Replace the two f64::powi calls (bloom false-positive-rate, FMP backoff timer)
with a shared core-only square-and-multiply helper in proto/math, bit-identical
to std::powi (a guard test pins this against every exponent the codecs reach),
and route the diagnostic estimated-count natural log through libm::log. The FPR
reject decision and the backoff timer are bit-for-bit unchanged; only the
debug-only count estimate may differ by at most one ULP.
Introduce a shared proto/codec module with a cursor Reader (short reads fail with
MessageTooShort { expected: position + needed, got: total }) and an append Writer,
and adopt them across the seven subsystem wire codecs, replacing the repetitive
manual slicing, try_into, and from_le_bytes extraction. Each existing length check
maps to the reader (an up-front minimum becomes require at position zero, so the
per-field expected values, including the tree-announce expected 99, are reproduced
exactly); the bloom exact-length check stays explicit since it also rejects
over-long payloads. Encoded bytes and decode decisions are unchanged.
Replace Malformed(String) with a no_std-clean set: Malformed(&static str)
for the static decode diagnostics, BadSizeClass { got, max } for the two
bloom size-class checks, and typed sources BadCoord(CoordError) /
BadBloom(BloomError) for the coordinate and bloom construction failures. Add a
dedicated CoordError so proto/coord no longer depends upward on stp TreeError,
resolving the temporary inversion from the coordinate relocation. Drop the
thiserror derive from the four proto error types (Error, TreeError, BloomError,
CoordError) in favor of hand-rolled core::fmt::Display and core::error::Error
impls. thiserror remains in use elsewhere in the crate. Wire decode decisions
are unchanged; only the error type and its diagnostic text change.
Hoist the two line-for-line-identical per-destination minimum-interval limiters
(discovery forward, routing error) into a shared PerAddrRateLimiter, and fold
the duplicated exponential-backoff math (discovery originator, FMP retry) into a
shared backoff_ms helper, both in a new proto/rate_limit module. The subsystem
limiters become thin delegating newtypes so should_forward/should_send and the
backoff call conventions are preserved. Behavior is byte-identical.
Two behavior-neutral relocations, wire bytes unchanged:
- Move the ParentDeclaration type and its impls out of state.rs into a dedicated
declaration.rs, re-exported at the same path, and relocate the inline wire.rs
test module into tests/wire.rs alongside the other stp unit tests (reusing the
shared test helpers). wire.rs drops to non-test code only.
- Move TreeCoordinate, CoordEntry, and the coordinate wire codec out of
proto/stp into a shared proto/coord module (a peer of proto/link), re-exported
from proto::stp so every existing import path keeps resolving unchanged.
Coordinate is a shared addressing primitive with many non-stp consumers, so it
no longer belongs under the spanning-tree subsystem. The codec carries a
documented temporary dependency on stp::TreeError until a dedicated CoordError
is introduced.
evaluate_parent no longer reads the injected clock: it returns a ParentEval of
Mandatory, Discretionary, or None, and the flap/hold-down veto is applied at the
edge via a new TreeState::is_switch_suppressed(now_ms), gating only the
discretionary arm. classify_announce/classify_periodic take the pre-computed
switch_suppressed bool instead of now_ms, so the whole classify ladder is
clock-free; the shell callers (tree announce/periodic re-eval, MMP first-RTT
re-eval, handle_parent_lost) compute the veto verdict. The no-coords parent
case stays discretionary (veto-gated) exactly as before. Behavior unchanged;
the veto tests now assert the moved responsibility.
Reorganize the MMP subsystem, behavior unchanged throughout:
- Restore the pre-migration role split: move SenderState into sender.rs,
ReceiverState (with its GapTracker helper) into receiver.rs, MmpMetrics and
RrLog into metrics.rs, and PathMtuState into path_mtu.rs, leaving the Mmp
aggregate plus the peer/session state in state.rs (1339 to 196 lines). Home
the module constants in a new limits.rs and re-export them at the same paths.
Pure code-motion with module rewiring; visibility unchanged.
- Dissolve the 97-line src/mmp shell, which held only MmpConfig and the
monotonic mono_ms() clock: move MmpConfig into config/node.rs (re-exported as
crate::config::MmpConfig), move mono_ms() into a new top-level src/time.rs
shell time seam, repoint all callers, and delete src/mmp/. Also correct stale
src/mmp/ doc-comment path labels to proto/mmp/ where they name the protocol
primitives.
Two behavior-neutral discovery cleanups:
- Move MAX_RECENT_DISCOVERY_REQUESTS out of the node discovery handler into the
discovery subsystem limits module and re-export it, keeping the two use sites
unchanged. Same value and semantics; only its home moves.
- Remove the ambient rand draw from LookupRequest by deleting generate() and
having the shell draw the random request_id and pass it into the existing
new() constructor. Same per-request u64 draw, now at the shell, leaving the
discovery codec free of ambient RNG reads.
The false-positive-rate primitive (fill ratio raised to the hash count) was
inlined at three sites. Hoist it into a BloomFilter::fpr() method and call it
from all three; the threshold/policy logic stays at the call sites. Behavior
and result bytes are unchanged.
Forward-merge the sans-IO cleanup series (bloom fpr, discovery const/RNG-injection,
mmp state decomposition, mmp shell dissolution, STP clock-free classify core, STP
declaration split, shared proto/coord relocation, shared rate limiter/backoff,
typed proto errors dropping thiserror, shared bounds-checked codec reader/writer,
core/alloc import sweep, no_std-shaped filter math) onto the next wire-format line.
Reconciled master structure against the next wire semantics: the mmp role-module
split adopts next slim report format (spin-bit stays dropped, sender/receiver
build next reports), the discovery and fmp codecs keep next TLV and profile
negotiation while moving to the typed error, and the parent-eval handler keeps the
Full/Leaf profile filter under the new ParentEval/is_switch_suppressed seam.
Forward-merge the FSP session-protocol sans-IO migration and the src/protocol
teardown from the master-refactor line onto next. Converge proto/fsp across
both lines (core.rs byte-identical), keeping next's born-on-next residue: the
additive SessionSetup/SessionAck wire variants, the spin-bit-less unit
FspInnerFlags, and the XX handshake shell residue (negotiation-payload
piggyback, initiator identity check, min-size length checks) in
handlers/session.rs. src/protocol is removed on next as well; ProtocolError,
LinkMessageType, and SessionDatagram reach their proto/ homes.
Migrate the FSP end-to-end session subsystem into src/proto/fsp/ following the
established sans-IO shape, and retire the src/protocol grab-bag now that FSP was
its last occupant.
Relocate the FSP session wire (node/session_wire.rs plus the FSP message types
from protocol/session.rs) into proto/fsp/wire.rs. Hoist the pure decision logic
into proto/fsp/core.rs over plain-data SessionSnapshots returning an ordered
FspAction list the shell drives: session-rekey policy, msg3-resend
classification, post-decrypt epoch reaction, setup/dual-init tie-break,
coords/path-MTU emit-policy, bounded pending-queue, and IPv6 ECN. The
crypto-owning SessionEntry stays shell-side in node/session.rs (matching the FMP
ActivePeer pattern); proto/fsp is wire + core + limits only, with no proto->noise
dependency and no crypto.
Move the coords helpers to proto/stp/ (they serialize TreeCoordinate), and split
SessionMessageType: the encrypted-inner 0x10-0x1F variants stay in proto/fsp/wire.rs
while the 0x20-0x2F routing signals become a new RoutingSignalType in
proto/routing/wire.rs. Migrate the session-MMP shell adapter, which continues to
drive proto/mmp/.
Retire src/protocol: LinkMessageType and SessionDatagram move to a new shared
proto/link.rs, ProtocolError becomes proto::Error (relocated verbatim), the
deprecated MessageType alias and the unimported PROTOCOL_VERSION are dropped, and
src/protocol/ is deleted along with its lib.rs module declaration.
Behavior-neutral: wire bytes unchanged, oracle tests pass unedited except
mod-path relocation; adds rekey/epoch characterization tests and pure
poll/emit-policy core tests.
Forward-merge the master-line bloom relocation into the next line,
discarding next's v1.5 bloom draft (RLE codec, XOR-diff delta,
FilterNack/0x21, adaptive sizing) and converging both lines onto the
identical proto/bloom v1-sans-IO module. This is a deliberate,
temporary wire regression on the next line: the v2 bloom is rebuilt
fresh, sans-IO from day one, on both lines later. Nothing outside the
bloom feature depended on the v1.5-specific surface. proto/bloom is now
byte-identical across both integration lines.
Migrate the v1 bloom filter subsystem into src/proto/bloom/, matching the
discovery/routing/fmp/mmp/stp reference layout and completing the proto/
relocation series for the data/wire subsystems.
- wire.rs: the FilterAnnounce (0x20) codec, moved from protocol/filter.rs
- core.rs: the pure BloomFilter algorithm (hash/insert/contains/merge/
as_bytes/from_bytes/estimated_count), moved from bloom/filter.rs
- state.rs: BloomState (per-peer inbound store, compute_outgoing_filter,
the injected-clock send debounce), moved from bloom/state.rs
- limits.rs: the v1 sizing constants
- mod.rs: module wiring + the BloomError enum
- tests/: the unit suite split by target (core/state/wire), no inline tests
no_std+alloc hygiene: core::fmt over std::fmt, the tracing dependency
dropped from the pure filter, and std collections replaced with
BTreeMap/BTreeSet (NodeAddr: Ord) for deterministic iteration. The pure
filter combination stays a BloomState method; the two irreducible shell
gathers (peer_inbound_filters, build_filter_announce) remain in the async
shell. Wire bytes and observable behavior are unchanged; full local CI
green (36/36) including the bloom-storm chaos gate.
Forward-merge the STP sans-IO migration. The classify / proto-stp structure,
clock injection, crypto field-partition, and BTree collections come from the
master line; next's non-full/leaf parent-candidacy skip is preserved by passing
self.non_full_peers() at the four shell call sites (handle_tree_announce,
check_periodic_parent_reeval, the MMP first-RTT re-eval, and the greedy-tree
find_next_hop fallback) instead of an empty set, with non_full_peers returning a
BTreeSet. next's four non_full_peers skip tests fold into proto/stp/tests.
Migrate the full non-async spanning-tree surface into proto/stp/, mirroring the
discovery/routing/fmp/mmp conversions. The classification ladder (parent-switch /
self-root / loop-drop / ancestry-update / periodic-rebroadcast / parent-lost) moves
out of the async node handlers into a pure Stp classify layer returning a
TreeDecision the shell drives, with effect ordering and per-arm invalidation
preserved verbatim. src/tree/ relocates wholesale: TreeState + ParentDeclaration data
+ coordinates into proto/stp/{state,coordinate}, the flap-dampening / hold-down
cluster into a FlapDampener in limits.rs, and the wire codec into wire.rs. The clock
is injected as u64 (wall-clock secs for the escaping declaration timestamp, monotonic
ms for the dampening timers via mmp::mono_ms); declaration crypto is field-partitioned
so sign/verify/hash run in the shell while the in-core modules carry data +
signing_bytes only. Peer maps/sets move to BTree; core/state/coordinate/limits are
core+alloc clean, with wire.rs the one std-tethered file. Behavior-neutral:
characterization tests added for the handler decision arms; convergence suite and
ci-local (36/36) green.
Forward-merge the master-side sans-IO refactor (discovery migration + no_std
reductions, collapsed to one commit) into the next-side branch. The discovery
decision core meets next's FMP profile/LookupRequest delta here: next's four
transit-forward predicates (Leaf no-forward, Full-profile, min_mtu, tree/fallback)
are folded into the pure core planners via an extended RoutingView seam
(node_is_leaf / peer_is_full / peer_meets_mtu, new ForwardOutcome::LeafNoForward),
and next's v2 LookupRequest API delta (origin_coords removed, tlv_entries added)
is reconciled across the discovery test tree, with next's four TLV wire tests
ported into the relocated wire test module.
The master-side branch now also carries the no_std+alloc reductions (BTreeMap,
alloc::sync::Arc, backoff-reset log moved to the shell, extern crate alloc),
which come through cleanly on the pilot-only core files.
Validated: cargo fmt / clippy (-D warnings) / test --lib all green, including
next's own transit MTU-pruning integration tests driving the refactored core
through the full shell path.
Migrate the FMP discovery decision logic out of the async handlers into
synchronous, runtime-agnostic sans-IO state machines owned by the protocol
structs, with I/O pushed to the edges. Pulls the full decision surface into a
pure core (backoff, rate-limit, planners, response routing), consolidates the
tests into a per-module tree with a shared crate testutil, and injects a u64
wall-clock so the core is free of Instant and std time.
Also brings the module toward no_std+alloc: the four discovery maps use
alloc::collections::BTreeMap (HashMap's RandomState is std-only), Arc is spelled
alloc::sync::Arc, the backoff-reset log lives in the shell (the core returns the
cleared count so observability stays out of the pure core), and the crate root
names alloc directly. The one remaining tether is ProtocolError's
std::error::Error coupling in the wire codec.
First subsystem of the broader sans-IO refactor; establishes the extraction
patterns and conventions carried forward to the remaining protocols.
handle_peer_removal_tree_cleanup reparents or self-roots the node when
its parent link drops, but omitted the coordinate-cache invalidation that
every other position-change path performs. Cached entries for downstream
destinations kept the node's now-stale coordinate prefix, and because
find_next_hop refreshes the TTL on every routing access, an actively
routed stale entry never self-expired — corrected only by a fresh insert.
Mirror the loop-detection branch: inside the parent-loss changed block,
invalidate both classes — invalidate_via_node (reparent) and
invalidate_other_roots (self-root). Add regression tests for a parent-link
removal that reparents (via-node entry dropped, same-root sibling
preserved) and one that self-roots (both via-node and stale old-root
entries dropped).
Add a "Running CI locally" section to testing/README.md covering the
ci-local.sh orchestrator: the per-run FIPS_CI_RUN_ID override and how it
scopes compose projects, image tags, and per-chaos-child subnets so
simultaneous runs on one host never collide; the cancellation exit codes
(130/143 vs 0/1) and how a preempting worker interprets them; and the
label-based cleanup via --reap / ci-cleanup.sh.
A CI worker may preempt an in-flight ci-local.sh run (SIGTERM, then SIGKILL
after a grace period) to restart on a newer commit. For that kill to be safe,
the script must clean up after itself and never let a dying run collide with
its restart. It previously had no signal handling, shared the default compose
project name across runs, and tore down each suite only at the suite end.
- Derive a per-run id (honoring FIPS_CI_RUN_ID, else short-sha+random) and
namespace every docker resource to it: a fipsci_<run>_<suite> compose project
per suite and per parallel chaos child, and per-run image tags
(fips-test:<run>, fips-test-app:<run>) retagged to :latest only after both
builds succeed so :latest never points at a half-built image.
- Install a bounded, idempotent teardown trap on SIGTERM/SIGINT (+ EXIT): reap
parallel chaos children, then force-remove this run's docker resources via
the new ci-cleanup.sh, wrapped in timeout so a stuck down cannot wedge it.
- Exit 143 (SIGTERM) / 130 (SIGINT), distinct from 0 (pass) / 1 (failed), so a
preempting worker tells a cancelled run from a real failure.
- Add ci-cleanup.sh (also ci-local.sh --reap): force-removes leftover CI
resources by the com.corganlabs.fips-ci=1 label and the fipsci_ project
prefix, robust to however a prior run died.
- Label every per-suite docker resource so the label sweep reaps it after a
SIGKILL regardless of network name: direct docker run/network resources, the
sidecar compose services, and every per-suite compose network (acl-allowlist,
boringtun, firewall, nat, static, both tor suites, and the chaos generator
template). Parametrize the static/sidecar compose image refs so the per-run
tags are honored.
- Give each parallel chaos child a unique /24 from 10.30.x (a new --subnet
override on the sim CLI, assigned per-child in ci-local.sh) so parallel
children never collide on a shared docker subnet, and a chaos net can never
span a fixed-subnet suite (sidecar/static in 172.20.x). 10.30.x sits outside
docker's default-address-pool range, so an auto-assigned net cannot land on
it either; node IPs derive from the subnet, so no scenario config changes.
Replace the fixed post-first-rekey and post-second-rekey settle sleeps in
the rekey integration test, and the fixed-deadline baseline wait in the
interop test, with the deterministic wait_until_connected progress-aware
polling helper already used for the initial baseline convergence.
Each converted site fails fast with structured diagnostics when the mesh
is stuck and extends its deadline only while pairwise reachability is
still climbing, removing the wall-clock settle windows that produced
intermittent connectivity failures after a rekey.
Brings the v0.4.0 release line up to date on next without disturbing
the in-flight wire-format work; next keeps its own 0.6.0-dev version.
Linkage merge so later forward-merges land cleanly.
maint carries only its 0.4.1-dev version bump; master keeps its own
0.5.0-dev development version. Recorded as a linkage merge so later
forward-merges of real fixes land cleanly.