Comment 10 for bug 1976146

Code has landed to relax the lock handling. ubuntu/jammy/daily-live-20220531.log build log from a test build:

ubuntu-arm64 on Launchpad finished at 2022-05-31 06:52:45 (Successfully built)
===== Syncing Ubuntu mirror =====
Tue May 31 06:52:46 UTC 2022
===== Building britney =====
Tue May 31 06:57:56 UTC 2022

The build succeeded.

It must be noted that removing this locking DOES introduce a very small window when an rsync could break another in-progress image build, because although the byhash indices are kept around, debian-cd does not use them; so since the InRelease file is access first, followed by the Packages files, an rsync could race and cause the image build to access a too-new Packages file that fails checksum validation. The window when this could happen is fairly small and the side-effects of the current implementation are sufficiently buggy that I think we should still proceed with this code change.

Closing the bug.