Incorrect error message when attempting to flag an issue as anonymous user

Steps to repro:

1. Create a project which allows anonymous users to edit/browse issues
2. Browse to a board of that board anonymously (do not log in)
3. Attempt to flag an issue

The error message is not consistent in the case when you do not have permission to edit the issue. But when you do have edit permission it does not allow you to flag the issue which inhibits the feature from working.