$ git clone -n https://src.fedoraproject.org/rpms/roundcubemail.git /var/lib/mock/f40-build-2032885-47741/root/chroot_tmpdir/scmroot/roundcubemail
Cloning into '/var/lib/mock/f40-build-2032885-47741/root/chroot_tmpdir/scmroot/roundcubemail'...
$ git fetch origin b762d330fac936d6d309748e5ca0a0644ba2f31a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/roundcubemail
 * [new ref]         b762d330fac936d6d309748e5ca0a0644ba2f31a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b762d33 v1.6.5