$ git clone -n https://src.fedoraproject.org/rpms/messagelib.git /var/lib/mock/f40-build-768685-125374/root/chroot_tmpdir/scmroot/messagelib
Cloning into '/var/lib/mock/f40-build-768685-125374/root/chroot_tmpdir/scmroot/messagelib'...
$ git fetch origin b8456a4599d963529abb2765bc5c739f33993c41:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/messagelib
 * [new ref]         b8456a4599d963529abb2765bc5c739f33993c41 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b8456a4 Added patch to change the HTML bar into a simple button