$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v9.0-u-ydi1-11109-29523/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v9.0-u-ydi1-11109-29523/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 187b0cd64e6ec11dba5ccce49deefc02819596b8:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         187b0cd64e6ec11dba5ccce49deefc02819596b8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 187b0cd bump release for test build