$ git clone -n https://src.fedoraproject.org/rpms/libXvMC.git /var/lib/mock/f45-build-15802-479/root/chroot_tmpdir/scmroot/libXvMC
Cloning into '/var/lib/mock/f45-build-15802-479/root/chroot_tmpdir/scmroot/libXvMC'...
$ git fetch origin fc306375f607ab85d1d3c92168e891b451dbea46:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libXvMC
 * [new ref]         fc306375f607ab85d1d3c92168e891b451dbea46 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fc30637 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild