$ git clone -n https://src.fedoraproject.org/rpms/ghc-gitrev.git /var/lib/mock/f41-build-837910-159471/root/chroot_tmpdir/scmroot/ghc-gitrev
Cloning into '/var/lib/mock/f41-build-837910-159471/root/chroot_tmpdir/scmroot/ghc-gitrev'...
$ git fetch origin dd61e1976ea86922cce3d91ff104a08770219d01:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-gitrev
 * [new ref]         dd61e1976ea86922cce3d91ff104a08770219d01 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dd61e19 bump release