$ git clone -n https://src.fedoraproject.org/rpms/gcl.git /var/lib/mock/f38-build-side-42-init-devel-1386537-30706/root/chroot_tmpdir/scmroot/gcl
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1386537-30706/root/chroot_tmpdir/scmroot/gcl'...
$ git fetch origin b2e3416e90ae3df7fc8dfc52a82f62287836488b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gcl
 * [new ref]         b2e3416e90ae3df7fc8dfc52a82f62287836488b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b2e3416 Update to 2.6.15pre3.