ConcurrentExternalFetch raced eight threads through GitFetch only.
BuildExternal takes the same lock on a line of its own, so that line
could go without any test noticing. Now that the configurations of one
pass share a single BuildExternal, its lock is what keeps two
crafter-builds, or two passes, out of each other's pulls.
The same threads now fetch through both, each into a clone of its own,
and both clones must end at the last round. With the lock in
BuildExternal removed, the test failed in two of three runs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Jorijn van der Graaf
7b548b9ce4