#333060 by merlinofchaos, dvessel, neclimdul: Prevent parent theme clobbering.

includes/theme.inc

@@ -776,6 +776,12 @@ function drupal_find_theme_functions($cache, $prefixes) {
         $templates[$hook] = array(
           'function' => $prefix . '_' . $hook,
         );
+        // Ensure that the pattern is maintained from base themes to its sub-themes.
+        // Each sub-theme will have their functions scanned so the pattern must be
+        // held for subsequent runs.
+        if (isset($info['pattern'])) {
+          $templates[$hook]['pattern'] = $info['pattern'];
+        }
       }
     }
   }
@@ -841,6 +847,12 @@ function drupal_find_theme_templates($cache, $extension, $path) {
         'path' => dirname($file->filename),
       );
     }
+    // Ensure that the pattern is maintained from base themes to its sub-themes.
+    // Each sub-theme will have their templates scanned so the pattern must be
+    // held for subsequent runs.
+    if (isset($cache[$hook]['pattern'])) {
+      $templates[$hook]['pattern'] = $cache[$hook]['pattern'];
+    }
   }
 
   $patterns = array_keys($files);