$ git clone -n https://src.fedoraproject.org/rpms/metacity.git /var/lib/mock/f42-build-side-1-3541377-46580/root/chroot_tmpdir/scmroot/metacity
Cloning into '/var/lib/mock/f42-build-side-1-3541377-46580/root/chroot_tmpdir/scmroot/metacity'...
$ git fetch origin 8f6a570b9794474506a1b821037bcaff9959ff4c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/metacity
 * [new ref]         8f6a570b9794474506a1b821037bcaff9959ff4c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8f6a570 Update to 3.56.0 (rhbz#2362445)