$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10288-28860/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10288-28860/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 431b8e8dbaf06fe6cc781c2fd2b43c332a6c9028:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         431b8e8dbaf06fe6cc781c2fd2b43c332a6c9028 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 431b8e8 bump release for test build