If log message is an array, feeds_log produces error: SQLSTATE[21S01]

When uploading a file and a line contains an error, feeds produces a message

Line 184 plugins/FeedsProcessor.inc :

...
if ($state->failed) {
      $messages[] = array(
       'message' => format_plural(
          $state->failed,
          'Failed importing @number @entity',
          'Failed importing @number @entities',
          array('@number' => $state->failed) + $tokens
        ),
        'level' => WATCHDOG_ERROR,
      );
}
...

The message array causes an array when log query is executed at feeds.module line 726.

Error:
SQLSTATE[21S01]: Insert value list does not match column list: 1136 Column count doesn't match value count at row 1