$ git clone -n https://src.fedoraproject.org/rpms/mutter.git /var/lib/mock/f40-build-797057-141055/root/chroot_tmpdir/scmroot/mutter
Cloning into '/var/lib/mock/f40-build-797057-141055/root/chroot_tmpdir/scmroot/mutter'...
$ git fetch origin 701f786699797ad9d5a7381e4649f528ac6b7581:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mutter
 * [new ref]         701f786699797ad9d5a7381e4649f528ac6b7581 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 701f786 Update to 46.0