$ git clone -n https://src.fedoraproject.org/rpms/rubygem-log4r.git /var/lib/mock/f45-build-35056-693/root/chroot_tmpdir/scmroot/rubygem-log4r
Cloning into '/var/lib/mock/f45-build-35056-693/root/chroot_tmpdir/scmroot/rubygem-log4r'...
$ git fetch origin 8e6ef7bae27fa741644df7efc878d225a27c7d40:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-log4r
 * [new ref]         8e6ef7bae27fa741644df7efc878d225a27c7d40 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8e6ef7b Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild