$ git clone -n https://src.fedoraproject.org/rpms/libmatroska.git /var/lib/mock/f45-build-16533-487/root/chroot_tmpdir/scmroot/libmatroska
Cloning into '/var/lib/mock/f45-build-16533-487/root/chroot_tmpdir/scmroot/libmatroska'...
$ git fetch origin 9109b5d09e5661a204d0ffeab51c26bf6546e780:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libmatroska
 * [new ref]         9109b5d09e5661a204d0ffeab51c26bf6546e780 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9109b5d correct license field