Hello.
I have found some 404 page.
On the local test Jira on the page
http://localhost:8081/browse/GH-3#
has button Configure for Bitbucket. If I press this button, then opened 404 page with link http://localhost:8081/secure/admin/ConfigureBitbucketOAuth!default.jspa

Oops, you've found a dead link.
Go back to the previous page
Go to the Home Page

Is it bug?
Sorry my bad English.
Best regards, Arthur Khusnutdinov.