Turns out this was because the configuration included transfer.fsckObjects=true. Without that option, git does not check the received objects.

git fsck reports:

error in tag e5b831b107ad18e78ec9ea5e6da68eb30bf71126: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag 88955494ad8f94a103c79a1f1bbab92fd8f3df65: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag 5af154997df3d681013019273c7c9ecdb12e1f69: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag f4203442e5c2ce8126de95982300989e8108fa16: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag e34dde73595136d47ca904ffe8a3ade61fdd0b26: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag 29e5b9c44e8776092998d222002212e5e15777e9: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag f2e47d0ecf97d82983e0e5d1a3ee6e7cc7096694: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag 462062f4f5256fff9a820675731a39950295b116: missingSpaceBeforeDate: invalid author/committer line - missing space before date
error in tag 0e1f8ca5fc828e57148b17f949ad802b162544d9: missingSpaceBeforeDate: invalid author/committer line - missing space before date

Corresponding to the tags:

RELEASE_0_9_2
RELEASE_1_0_0
RELEASE_1_0_2
SNAPSHOT_0_1_1
SNAPSHOT_0_1_2
SNAPSHOT_0_1_3
SNAPSHOT_0_1_4
SNAPSHOT_0_1_5
SNAPSHOT_0_1_6

Still, I think the repository should not include bad tags. Maybe they can be recreated with something like this:

fixup() {
  GIT_COMMITTER_DATE="$(git log -1 --pretty=%cI $1)" \
  git -c user.name='Carl Worth' -c user.email='cworth@cworth.org' \
      tag -f -m '' $1 $1'^{commit}'
}

The tags could be recreated, but that tends to make people uneasy.

They're historical and not signed, either.

The more important tags such as 1.0.0 (which tags the same commit as RELEASE_1_0_0 but is signed) and later would not be touched.

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/cairo/cairo/issues/145.