Symptoms

1. Click a 'Clone in SourceTree' link in Bitbucket or Stash
2. You receive an error along the lines of 'sourcetree:// doesn't have any registered protocol handlers'

Cause

Mac OS X's Launch Services database hasn't been updated when SourceTree 1.4 was installed. It appears that the auto-update system (Sparkle) doesn't trigger the database update, but dragging / dropping a new .app into Applications in Finder does.

Resolution

1. To rebuild your Launch Services database, in a terminal, run the following command:

   /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user
   

2. Alternatively, re-download SourceTree from the website and drag it from the image into /Applications in Finder, which will cause Launch Services to refresh