TYPO3 Core

function cropMbstring($charset, $string, $len, $crop = '')

as always, $len can also be negative and is correctly handled.

But the check, weather the string should really be truncated is as followed:
if (intval($len) == 0 || mb_strlen($string) < $len) {
return $string;
}

So, if $len < 0, we never return here, but later prepend "...".

Solution: check length < abs($len)

One example, where this can be seen is the pagepath on the top right.
(issue imported from #M12297)