[tannevaled]

What broke, and why nothing was committed

ubuntu-latest became Ubuntu 26.04 on 2026-10-19. There qemu-user-static is a virtual package and apt refuses to choose between its two providers:

E: Package 'qemu-user-static' has no installation candidate
Package qemu-user-static is a virtual package provided by:
  qemu-user-binfmt-hwe 1:10.2.1+ds-1ubuntu4.4
  qemu-user-binfmt     1:10.2.1+ds-1ubuntu3.3

The step exits 100 in about twenty seconds. This lane went red between a green main and the next push with nothing committed here. 333 repositories in 258 organisations of this account carried the same line; this is part of that sweep.

Two things that are not the fix

• ⚠ Installing a provider. qemu-user-binfmt registers binfmt handlers; it does not ship the qemu-<arch>-static binaries this lane invokes. A lane given only a provider takes its command -v branch and goes green while testing nothing — worse than red. qemu-user ships the dynamic qemu-<arch>, which is all go test -exec needs, so both packages are installed and both binary names are accepted at run time.
• ⛔ Skipping when the emulator is missing. A missing emulator now fails this lane, and the lane prints which emulator it ran (running ppc64le under qemu-ppc64le). Without that line, "ran under emulation" and "skipped" are indistinguishable from a green tick — which is how a fix for this looks like it worked while testing nothing. Check that line in the lane's log, not the tick.

What did not change

Nothing but the package names and the emulator lookup. Where there was a bounded, retried apt loop it is kept — it answers a measured apt outage, which is a different defect. CGO_ENABLED=0, the test timeouts and the package lists are carried through verbatim: those were decisions somebody took.

How it was written

By qemufix v0.37.0 (go-fleettools/fleettools#128): a tested Go tool that recognises four workflow shapes, refuses by name anything else rather than guessing, and is idempotent — an already-fixed file comes back byte-identical and is reported already-fixed. Its tests assert the three invariants per shape, with a control that runs the invariant checkers against the unfixed input, and a planted positive for the idempotence claim.

Verified on the first merged lane of this campaign: the log reads running <arch> under <emulator> and the packages pass under emulation (see go-tex/engine#645).

🤖 Generated with Claude Code