When a custom logo is configured but has a restrictive visibility policy, fall back to the default logo

Summary: Fixes T11982. Currently, configuring a custom logo and then setting the policy restrictively locks off the whole install.

Test Plan:
  - Configured `ui.logo`.
  - Searched for the file PHID in global search to find the underlying file.
  - Set the policy to something restrictive ("only me").
  - Purged cache (`bin/cache purge --purge-all`).
  - Restarted webserver to nuke APC.
  - Loaded a page as a different user.
  - Before change: policy exception while trying to load the logo.
  - After change: fallback to default logo.
  - Loaded page as user who can see the logo, got custom logo.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11982

Differential Revision: https://secure.phabricator.com/D17011

src/view/page/menu/PhabricatorMainMenuView.php

@@ -317,20 +317,27 @@ final class PhabricatorMainMenuView extends AphrontView {
 
       $logo_uri = $cache->getKey($cache_key_logo);
       if (!$logo_uri) {
-        $file = id(new PhabricatorFileQuery())
+        // NOTE: If the file policy has been changed to be restrictive, we'll
+        // miss here and just show the default logo. The cache will fill later
+        // when someone who can see the file loads the page. This might be a
+        // little spooky, see T11982.
+        $files = id(new PhabricatorFileQuery())
           ->setViewer($this->getViewer())
           ->withPHIDs(array($custom_header))
-          ->executeOne();
+          ->execute();
+        $file = head($files);
         if ($file) {
           $logo_uri = $file->getViewURI();
           $cache->setKey($cache_key_logo, $logo_uri);
         }
       }
 
+      if ($logo_uri) {
         $logo_style[] = 'background-size: 40px 40px;';
         $logo_style[] = 'background-position: 0 0;';
         $logo_style[] = 'background-image: url('.$logo_uri.')';
       }
+    }
 
     $logo_node = phutil_tag(
       'span',