$ git clone -n https://src.fedoraproject.org/rpms/ghc-serialise.git /var/lib/mock/f39-build-1930419-43108/root/chroot_tmpdir/scmroot/ghc-serialise
Cloning into '/var/lib/mock/f39-build-1930419-43108/root/chroot_tmpdir/scmroot/ghc-serialise'...
$ git fetch origin f9d0d01d41418c18c61b1c94187c4cc14b6972f2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-serialise
 * [new ref]         f9d0d01d41418c18c61b1c94187c4cc14b6972f2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f9d0d01 revised .cabal file