$ git clone -n https://github.com/xcp-ng-rpms/python /var/lib/mock/v8.3-u-prebuild-9181-27988/root/chroot_tmpdir/scmroot/python
Cloning into '/var/lib/mock/v8.3-u-prebuild-9181-27988/root/chroot_tmpdir/scmroot/python'...
$ git fetch origin c57078db341b14a78edbc6e4f2ee976a6f2802d0:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/python
 * [new ref]         c57078db341b14a78edbc6e4f2ee976a6f2802d0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c57078d bump release for test build