$ git clone -n https://src.fedoraproject.org/rpms/ghc-gitrev.git /var/lib/mock/f39-build-1507081-35224/root/chroot_tmpdir/scmroot/ghc-gitrev
Cloning into '/var/lib/mock/f39-build-1507081-35224/root/chroot_tmpdir/scmroot/ghc-gitrev'...
$ git fetch origin d2d50cd1d27c3f21d5f8f30c0d47810683ebdb37:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-gitrev
 * [new ref]         d2d50cd1d27c3f21d5f8f30c0d47810683ebdb37 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d2d50cd bump release