$ git clone -n https://src.fedoraproject.org/rpms/libnova.git /var/lib/mock/f42-build-866171-173785/root/chroot_tmpdir/scmroot/libnova
Cloning into '/var/lib/mock/f42-build-866171-173785/root/chroot_tmpdir/scmroot/libnova'...
$ git fetch origin 51f540e3d2211a487392158d683166666b39f066:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libnova
 * [new ref]         51f540e3d2211a487392158d683166666b39f066 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 51f540e Update to upstream tag v0.16 (fedora#2239660)