Switching branches by dropdown in source browser fails to refresh file list (BB-9632)

When browsing the source directories, using the "branch" dropdown:

...doesn't affect any changes to the source view. Tested with Firefox 25.0.1 on Win XP.

When switching branches while a source file is open in the browser, if it doesn't exist in the other branch, a 404 page is returned - so I presume the refresh only fails in the directory view.