Comment 0 for bug 1397114

Due to mutable dictionary being used as the default `target` argument value the first target calculated from scratch in POLICY_CHECK function will be used for all subsequent calls to POLICY_CHECK with 2 arguments. The wrong `target` can either lead to a reduced set of permissions on an entity for a given user, or to enlarged one. Due to independent policy checks at each service side this doesn't pose a serious security breach, but can lead to weird UX behaviour.