All module paths should be absolute, not relative to drupal root. See...

All module paths should be absolute, not relative to drupal root. See https://drupal.org/node/2162691

lib/DrupalSystem/DrupalSystem.php

@@ -23,7 +23,7 @@ class DrupalSystem implements DrupalSystemInterface {
    * {@inheritdoc}
    */
   function drupalGetFilename($type, $name) {
-    return drupal_get_filename($type, $name);
+    return DRUPAL_ROOT . '/' . drupal_get_filename($type, $name);
   }
 
   /**

lib/DrupalSystem/DrupalSystemInterface.php

@@ -15,12 +15,13 @@ interface DrupalSystemInterface {
   function variableGet($name, $default = NULL);
 
   /**
-   * Replacement of drupal_get_filename().
+   * Replacement of drupal_get_filename(), but returning an absolute path.
    *
    * @param string $type
    * @param string $name
    *
    * @return string
+   *   The result of drupal_get_filename() with DRUPAL_ROOT . '/' prepended.
    */
   function drupalGetFilename($type, $name);