Avoid error in blaming empty file

Summary: Fixes T2389, resolves TODO.

Test Plan: Blamed seemingly binary file.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2389

Differential Revision: https://secure.phabricator.com/D4604

src/applications/diffusion/controller/DiffusionBrowseFileController.php

@@ -467,8 +467,6 @@ final class DiffusionBrowseFileController extends DiffusionController {
         // with same color; otherwise generate blame info. The newer a change
         // is, the more saturated the color.
 
-        // TODO: SVN doesn't always give us blame for the last line, if empty?
-        // Bug with our stuff or with SVN?
         $rev = idx($rev_list, $k, $last_rev);
 
         if ($last_rev == $rev) {