$ git clone -n https://src.fedoraproject.org/rpms/ghc-ObjectName.git /var/lib/mock/f39-build-1507013-35220/root/chroot_tmpdir/scmroot/ghc-ObjectName
Cloning into '/var/lib/mock/f39-build-1507013-35220/root/chroot_tmpdir/scmroot/ghc-ObjectName'...
$ git fetch origin 441fbf5597a483e8bfd06d0b91ae7adf0515d5eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-ObjectName
 * [new ref]         441fbf5597a483e8bfd06d0b91ae7adf0515d5eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 441fbf5 bump release