$ git clone -n https://src.fedoraproject.org/rpms/ghc9.0.git /var/lib/mock/f42-build-3357749-45030/root/chroot_tmpdir/scmroot/ghc9.0
Cloning into '/var/lib/mock/f42-build-3357749-45030/root/chroot_tmpdir/scmroot/ghc9.0'...
$ git fetch origin a9ba323a74517d3cfdde91277d14891ea62f0dd8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc9.0
 * [new ref]         a9ba323a74517d3cfdde91277d14891ea62f0dd8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a9ba323 use %ghc_merge_filelist