$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10240-28815/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10240-28815/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 5d2fe6cfb8d4881225ea0123dc7719f067941480:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         5d2fe6cfb8d4881225ea0123dc7719f067941480 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5d2fe6c bump release for test build