$ git clone -n https://github.com/xcp-ng-rpms/libtdb.git /var/lib/mock/v8.3-u-pcoval1-11141-29554/root/chroot_tmpdir/scmroot/libtdb
Cloning into '/var/lib/mock/v8.3-u-pcoval1-11141-29554/root/chroot_tmpdir/scmroot/libtdb'...
$ git fetch origin b533439f6204fa150ff0dd75c2f27fa704040e53:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libtdb
 * [new ref]         b533439f6204fa150ff0dd75c2f27fa704040e53 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b533439 bump release for test build