Fix local-clobbering iterators in phabricator/

Summary:
These are the issues identified by the linter in D2052. I don't think any cause bugs, but they are all reasonable errors to raise and the linter correctly
detected that they are suspicious.

Test Plan: Mostly inspection.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D2053

src/applications/diffusion/controller/home/DiffusionHomeController.php

@@ -61,9 +61,9 @@ final class DiffusionHomeController extends DiffusionController {
     $repository = new PhabricatorRepository();
 
     $repositories = $repository->loadAll();
-    foreach ($repositories as $key => $repository) {
-      if (!$repository->isTracked()) {
-        unset($repositories[$key]);
+    foreach ($repositories as $key => $repo) {
+      if (!$repo->isTracked()) {
+        unset($repo[$key]);
       }
     }