Fix project hashtag bugs: allow simultaneously changing name and adding same name as a tag master
Summary: Fixes T8509. Changes these behaviors: - If you create a project named "QQQ" and add "qqq" as a hashtag at the same time, it fails in an unhelpful way. (Now: succeeds.) - If you add "qqq" as a hashtag to a project with primary hashtag "qqq", it fails in a correct but probably unnecessary way (Now: just works). We could make one or both of these behaviors show the user an error instead, but I think it's likely that this behavior is just what they always want. Test Plan: - Added failing tests and made them pass. - Executed both scenarios described above from the web UI. Reviewers: chad Reviewed By: chad Maniphest Tasks: T8509 Differential Revision: https://secure.phabricator.com/D14871