$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10306-28875/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10306-28875/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 7f7e191b73b501fd7f2da569cb89d637dbe29955:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         7f7e191b73b501fd7f2da569cb89d637dbe29955 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7f7e191 bump release for test build