$ git clone -n https://github.com/xcp-ng-rpms/trousers.git /var/lib/mock/v8.3-u-pcoval2-10364-28927/root/chroot_tmpdir/scmroot/trousers
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10364-28927/root/chroot_tmpdir/scmroot/trousers'...
$ git fetch origin 66a7f9a313545e192cefd0ad5f6d59bc5c41e97c:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/trousers
 * [new ref]         66a7f9a313545e192cefd0ad5f6d59bc5c41e97c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66a7f9a bump release for test build