$ git clone -n https://github.com/xcp-ng-rpms/samba.git /var/lib/mock/v8.3-u-prebuild-9285-28059/root/chroot_tmpdir/scmroot/samba
Cloning into '/var/lib/mock/v8.3-u-prebuild-9285-28059/root/chroot_tmpdir/scmroot/samba'...
$ git fetch origin 6bf57cc52cfd07745f4ebf0ffdb268f63d0303dd:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/samba
 * [new ref]         6bf57cc52cfd07745f4ebf0ffdb268f63d0303dd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6bf57cc bump release for test build