test_qwen4_gate_record_and_changelog_are_discoverable_and_credited pinned
changelog.d/0.73.3/603.added.md by absolute path. Per-PR fragments are
consumed at release time by design (#487/#490), so assembling v0.74.0 deleted
the file the test opened and turned all nine cells red with a
FileNotFoundError -- an assembly that is supposed to happen, failing a test
whose subject is the credit rather than where the credit is stored.

It now reads CHANGELOG.md and any surviving 603 fragment and requires the
credit in whichever currently carries it, so it holds both before and after a
release. The gate-record assertion is unchanged.

Both assertions also gained failure messages naming the consequence, and the
"neither source is readable" case is asserted rather than silently passing on
an empty list.

Mutation-verified: removing `by @Amix29` from the assembled CHANGELOG.md entry
fails the test; restoring it passes. So the repair did not turn the test
vacuous, which is the obvious way to "fix" a red path-pinned test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>