$ git clone -n https://src.fedoraproject.org/rpms/rubygem-marc.git /var/lib/mock/f45-build-35086-693/root/chroot_tmpdir/scmroot/rubygem-marc
Cloning into '/var/lib/mock/f45-build-35086-693/root/chroot_tmpdir/scmroot/rubygem-marc'...
$ git fetch origin a132702684dd3d7ef6129b1db3161b762ccf8a76:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-marc
 * [new ref]         a132702684dd3d7ef6129b1db3161b762ccf8a76 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a132702 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild