User without any permission can be a watcher

[drookie]

I have some Jira local users and their LDAP "clones"  (merely because the LDAP catalogue was created some time after Jira was set up). The only issue with that that they are easily mixed when assigning the issue watchers. The thing that bothers me the most is - that a LDAP "clone" of the local user cannot login to Jira since it has no "Jira software" check set in his properties, but in the same time it appears in the "Assign watcher" search field. And this is the only field where these clones make a real issue. They don't appear in the "Assignee" field since they don't have the privilege to log in.

How can I exclude them from watchers field search results ?