$ git clone -n https://github.com/xcp-ng-rpms/python /var/lib/mock/v8.3-u-prebuild-9173-27988/root/chroot_tmpdir/scmroot/python
Cloning into '/var/lib/mock/v8.3-u-prebuild-9173-27988/root/chroot_tmpdir/scmroot/python'...
$ git fetch origin ff4a5da4a527a2037618dcdf12e6d00d66945c02:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/python
 * [new ref]         ff4a5da4a527a2037618dcdf12e6d00d66945c02 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ff4a5da bump release for test build