Open editor from stack trace

Summary:
I've considered that user may have set editor but not checked out Phabricator repositories.
But stack trace is useful mainly for developers.

Test Plan:
Click on path in Unhandled Exception.
Repeat with disabled editor.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2107

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

@@ -256,7 +256,8 @@ final class DifferentialChangesetListView extends AphrontView {
         $changeset->getAbsoluteRepositoryPath($this->diff, $repository),
         '/');
       $line = 1; // TODO: get first changed line
-      $editor_link = $user->loadEditorLink($path, $line, $repository);
+      $callsign = $repository->getCallsign();
+      $editor_link = $user->loadEditorLink($path, $line, $callsign);
       if ($editor_link) {
         $meta['editor'] = $editor_link;
       } else {