Fix the "Browse in Diffusion" URI in Differential

Summary: Apparently I spent like a good month copy/pasting slightly different versions of this logic all over the codebase.

Test Plan: Selected "View Options -> Browse in Diffusion" for a chagneset, got a URI with a branch name in it under Git.

Reviewers: vrana, btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1993

src/applications/differential/view/changesetlistview/DifferentialChangesetListView.php

@@ -227,7 +227,7 @@ final class DifferentialChangesetListView extends AphrontView {
 
     $repository = $this->repository;
     if ($repository) {
-      $meta['diffusionURI'] = $repository->getDiffusionBrowseURIForPath(
+      $meta['diffusionURI'] = (string)$repository->getDiffusionBrowseURIForPath(
         $changeset->getAbsoluteRepositoryPath($this->diff, $repository));
     }