To be honest i have no clue why this happens, i hoped the included LC_TIME file might shine a light on it for someone more familiair with this subject.

$value is being reused in the next loop, when $value contains empty array it will cause notice with the concat on line 551, hence im replacing it with empty string.

Without the filter https://github.com/cakephp/cakephp/pull/1220/files#L2R86 causes a notice

This fix might be a case of suppresing errors in the wrong way, instead of avoiding the real cause.