Issue #1158322 follow-up by olli: Added missing backtrace to exception errors.

core/includes/errors.inc

@@ -122,6 +122,7 @@ function _drupal_decode_exception($exception) {
     '%file' => $caller['file'],
     '%line' => $caller['line'],
     'severity_level' => WATCHDOG_ERROR,
+    'backtrace' => $backtrace,
   );
 }