$ git clone -n https://src.fedoraproject.org/rpms/ghc-hashtables.git /var/lib/mock/f40-build-2047946-48979/root/chroot_tmpdir/scmroot/ghc-hashtables
Cloning into '/var/lib/mock/f40-build-2047946-48979/root/chroot_tmpdir/scmroot/ghc-hashtables'...
$ git fetch origin a8cba489d6ea3b894796aabe836549adde468ba3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-hashtables
 * [new ref]         a8cba489d6ea3b894796aabe836549adde468ba3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a8cba48 bump release