$ git clone -n https://src.fedoraproject.org/rpms/Carla.git /var/lib/mock/f39-build-1550793-36956/root/chroot_tmpdir/scmroot/Carla
Cloning into '/var/lib/mock/f39-build-1550793-36956/root/chroot_tmpdir/scmroot/Carla'...
$ git fetch origin a53bb1a6cf9a8774761caaeec35d81962f7f5bf1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Carla
 * [new ref]         a53bb1a6cf9a8774761caaeec35d81962f7f5bf1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a53bb1a Update to 2.5.7