$ git clone -n https://github.com/xcp-ng-rpms/trousers.git /var/lib/mock/v8.3-incoming-9097-27939/root/chroot_tmpdir/scmroot/trousers
Cloning into '/var/lib/mock/v8.3-incoming-9097-27939/root/chroot_tmpdir/scmroot/trousers'...
$ git fetch origin 2fcfcf053930a5ed8a2f304ed1ce59f53a6b358b:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/trousers
 * [new ref]         2fcfcf053930a5ed8a2f304ed1ce59f53a6b358b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2fcfcf0 Import trousers-0.3.15-1.xs8.src.rpm