Fix AttributeError when trying to accessing invalid diff fragment.
Review Request #6089 — Created July 9, 2014 and submitted
When browsing to an invalid FileDiff via, we would raise a 404
exception but this was getting caught prematurely and eventually
causing a server error. This change simply passes Http404 errors
back up the stack.
No unit tests for this but it would seem trivial to implement.
Tool: PEP8 Style Checker Processed Files: reviewboard/diffviewer/views.py Tool: Pyflakes Processed Files: reviewboard/diffviewer/views.py