$ git clone -n https://src.fedoraproject.org/rpms/ghc-Diff.git /var/lib/mock/f40-build-741914-110406/root/chroot_tmpdir/scmroot/ghc-Diff
Cloning into '/var/lib/mock/f40-build-741914-110406/root/chroot_tmpdir/scmroot/ghc-Diff'...
$ git fetch origin f1ff1eb1e52205cbfcbdc65b331cd4eec6d6b0d1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-Diff
 * [new ref]         f1ff1eb1e52205cbfcbdc65b331cd4eec6d6b0d1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f1ff1eb bump release