$ git clone -n https://src.fedoraproject.org/rpms/gstreamer1-plugins-ugly-free.git /var/lib/mock/f40-build-2236741-53519/root/chroot_tmpdir/scmroot/gstreamer1-plugins-ugly-free
Cloning into '/var/lib/mock/f40-build-2236741-53519/root/chroot_tmpdir/scmroot/gstreamer1-plugins-ugly-free'...
$ git fetch origin 2f3041ca172705abd6740d3ed94e0e7aabe46ec6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gstreamer1-plugins-ugly-free
 * [new ref]         2f3041ca172705abd6740d3ed94e0e7aabe46ec6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2f3041c Remove LGPL-2.1-only from spec