Mentions continues to suggest names indefinately after a @ even though we know we have no matches

1. Type this comment :"brenden @ this will continue to look for names well after any reasonable time".

Note that JIRA will continue to poll the server for each character to the end of the sentence. If you continued typing it would continue to poll the server. There is a point where it is clear that @ is not being used to reference a user. In this case we should not be polling the server.