renaming a Plan should prevent he old name from showing up

[Panaetius]

$ renku run --name name1 -- echo 'test' > A
$ renku workflow ls
ID                                       NAME
---------------------------------------  -------------------------
/plans/12d6e7020ff64490983dafb6890b7c56  name1
$ renku workflow edit --name new_name name1
$ renku workflow ls
ID                                       NAME
---------------------------------------  -------------------------
/plans/12d6e7020ff64490983dafb6890b7c56  name1
/plans/b010cab019524ecaa0e2e57b42ac435e  new_name

name1 should not show up anymore in the list above, i.e. it should be removed from the plans index