$ git clone -n https://src.fedoraproject.org/rpms/ghc.git /var/lib/mock/f41-build-1057800-19407/root/chroot_tmpdir/scmroot/ghc
Cloning into '/var/lib/mock/f41-build-1057800-19407/root/chroot_tmpdir/scmroot/ghc'...
$ git fetch origin 49c6e22be3aa1d1741bdcfd7c7d357d746f35da0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc
 * [new ref]         49c6e22be3aa1d1741bdcfd7c7d357d746f35da0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49c6e22 tweak comments for llvm/s390x patch and archs