$ git clone -n https://src.fedoraproject.org/rpms/xgap.git /var/lib/mock/f45-build-38893-730/root/chroot_tmpdir/scmroot/xgap
Cloning into '/var/lib/mock/f45-build-38893-730/root/chroot_tmpdir/scmroot/xgap'...
$ git fetch origin e531806b854d6297f8b18ef2697f1459f99e14e9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xgap
 * [new ref]         e531806b854d6297f8b18ef2697f1459f99e14e9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e531806 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild