Fix bad tables in diffusion blame

Summary: My fake data was 100%, and not all tables have full revision history. This leads to a broken table. Instead check if we have //any// revisions at all, then always show the column, with or without a link inside.

Test Plan: going on a limb this is the correct fix and test on secure... again ...

Reviewers: epriestley

Reviewed By: epriestley

Spies: Korvin

Differential Revision: https://secure.phabricator.com/D18474

src/applications/diffusion/controller/DiffusionBrowseController.php

@@ -1183,7 +1183,7 @@ final class DiffusionBrowseController extends DiffusionController {
           ),
           $commit_link);
 
-        if ($revision_link) {
+        if ($revision_map) {
           $row[] = phutil_tag(
             'th',
             array(