A tag found in the cache after the refresh failed was reported as
mirrored with no sign it might be stale, though tags can move. Keep
serving it, as a cached commit is, but log a warning naming the tag,
the commit and the refresh error.
A version that wasn't a lowercase full-length hex ID was taken for a
tag, so an uppercase commit ID failed as a missing tag. Lowercase a
full-length hex version first. A shorter hex version that names no tag
now fails saying it is neither a full commit ID nor a tag.
Looking for .gitmodules took any error from git cat-file as the file
not being there, so a mirror whose context was cancelled reported
success with no submodules. Use rev-parse --verify --quiet, whose exit
status 1 means the path is missing, and return other errors.
A .gitmodules git config can't parse failed the mirror of a commit that
is cached all the same. Log a warning and skip its submodules instead,
as an unserved submodule host is skipped.
git config --get-regexp exits 1 when nothing matches, which failed the
mirror of a commit with an empty .gitmodules. The submodules are now read
from --list.
A pkg:git version can now be a tag as well as a full commit ID. With a
version, the submodules the commit records are mirrored at the commits it
pins, from the upstream.git hosts serving them; one no host serves is
skipped with a warning.
Mirroring a commit on no branch or tag again writes a fresh wanted ref, so
its 7 days count from the last mirror run. A cached repository whose refresh
fetched new commits is no longer reported as cached.
proxy mirror, mirror API jobs and SBOMs take pkg:git/{host}/{path}@{commit}
and cache the repository and commit in the cache /git serves, so a later
clone is a cache hit, also with the upstream down. Part of #403.
