Xcode 7 GM can not authenticate git repository
The problem is that you are using the SSH remote URL:
remote.origin.url=git@bitbucket.org:myUserName/myProject.gitYou will need to switch to the HTTPS remote URL.
git remote set-url origin https://bitbucket.org/myUserName/myProject.gitAlternatively, just give up. Stop trying to use Xcode's internal git management. (It's pretty terrible, so no harm done.) If you want a GUI, use SourceTree; it's from the same people who give you Bitbucket and works with it beautifully.