Description:
------------
Bad character encoding detection when form is set enctype="multipart/form-data"
and mbstring.encoding_translation is On

Version PHP 5.2.14 and PHP 5.3.3 is OK


My php.ini:
.....
mbstring.language = Neutral
mbstring.internal_encoding = UTF-8
mbstring.encoding_translation = On
mbstring.http_input = auto
mbstring.http_output = UTF-8
.....

may be associated with https://bugs.php.net/bug.php?id=44624

Test script:
---------------
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<form enctype="multipart/form-data" method="post">
<input name="message" value="ěščřžýáíé">
<input type="submit">
</form>

...

<?php
echo $_POST['message'];  // ěščřžýáíé
echo mb_detect_encoding($_POST['message']);  // UTF-8
echo mb_http_input("P"); //false

echo $str = mb_convert_encoding($_POST['message'], "ISO-8859-1", "UTF-8"); // ěščřžýáíé
?>