$ git clone -n https://src.fedoraproject.org/rpms/libvpx.git /var/lib/mock/f45-build-17235-497/root/chroot_tmpdir/scmroot/libvpx
Cloning into '/var/lib/mock/f45-build-17235-497/root/chroot_tmpdir/scmroot/libvpx'...
$ git fetch origin 1b40b6e9406c7d4627d94fc827f1080a9d323660:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libvpx
 * [new ref]         1b40b6e9406c7d4627d94fc827f1080a9d323660 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1b40b6e 1.17.0