$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-9873-28590/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-9873-28590/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 87fd8ce313143e893e06253f276ad0aa0157aff6:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         87fd8ce313143e893e06253f276ad0aa0157aff6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 87fd8ce bump release for test build