$ git clone -n https://src.fedoraproject.org/rpms/seamonkey.git /var/lib/mock/f39-build-1972082-43325/root/chroot_tmpdir/scmroot/seamonkey
Cloning into '/var/lib/mock/f39-build-1972082-43325/root/chroot_tmpdir/scmroot/seamonkey'...
$ git fetch origin a605fcacde500143d6cecf8211e9f4be4ba708a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/seamonkey
 * [new ref]         a605fcacde500143d6cecf8211e9f4be4ba708a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a605fca .