do not re-use output when an exception occurs

Summary:
$stdout from the previous run would be reused if an exception
occurred

Test Plan: that's a negative, ghostrider.

Reviewers: epriestley, jungejason

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D2008

src/applications/diffusion/query/diff/svn/DiffusionSvnDiffQuery.php

@@ -99,6 +99,7 @@ final class DiffusionSvnDiffQuery extends DiffusionDiffQuery {
     $futures = array_filter($futures);
 
     foreach (Futures($futures) as $key => $future) {
+      $stdout = '';
       try {
         list($stdout) = $future->resolvex();
       } catch (CommandException $e) {