$ git clone -n https://src.fedoraproject.org/rpms/mkvtoolnix.git /var/lib/mock/f38-build-side-42-init-devel-927900-28745/root/chroot_tmpdir/scmroot/mkvtoolnix
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-927900-28745/root/chroot_tmpdir/scmroot/mkvtoolnix'...
$ git fetch origin 5881a362477a3e60947c9007080e1b7b140ff0ca:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mkvtoolnix
 * [new ref]         5881a362477a3e60947c9007080e1b7b140ff0ca -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5881a36 Merge branch 'f37' into f38