$ git clone -n https://github.com/xcp-ng-rpms/python /var/lib/mock/v8.3-u-prebuild-9192-27996/root/chroot_tmpdir/scmroot/python
Cloning into '/var/lib/mock/v8.3-u-prebuild-9192-27996/root/chroot_tmpdir/scmroot/python'...
$ git fetch origin 66cdbe31e23dd67c891a2801124d636deb463af8:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/python
 * [new ref]         66cdbe31e23dd67c891a2801124d636deb463af8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66cdbe3 bump release for test build