$ git clone -n https://github.com/xcp-ng-rpms/python.git /var/lib/mock/v8.3-incoming-9085-27939/root/chroot_tmpdir/scmroot/python
Cloning into '/var/lib/mock/v8.3-incoming-9085-27939/root/chroot_tmpdir/scmroot/python'...
$ git fetch origin 43fa23ce4a6ea6f879a2f4626de439bda697f700:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/python
 * [new ref]         43fa23ce4a6ea6f879a2f4626de439bda697f700 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 43fa23c Import python-2.7.5-92.xs8.src.rpm