$ git clone -n https://src.fedoraproject.org/rpms/xcb-proto.git /var/lib/mock/f40-build-2216706-52512/root/chroot_tmpdir/scmroot/xcb-proto
Cloning into '/var/lib/mock/f40-build-2216706-52512/root/chroot_tmpdir/scmroot/xcb-proto'...
$ git fetch origin a6f3e758debaaee3fb72b12b6d1ca4890c31b7cc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xcb-proto
 * [new ref]         a6f3e758debaaee3fb72b12b6d1ca4890c31b7cc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6f3e75 xcb-proto 1.16.0