This might be overly aggressive. Note the use case for `all_other_contexts=True`. This is when the user wants to manually remove all the keys, e.g. by running `make purge_cluster`. To do that, a context is created, and from that context, it asks the engines to delete everything, *except* for the stuff from the context used to ask for the deletion. In that case, I think that clearing the `self._comm_key` is probably incorrect.