Description:
------------
FILTER_VALIDATE_EMAIL is locale aware and produces different results depending on the locale set. Or more specific the \w escape sequence used in the regular expression is locale aware.

From http://www.php.net/manual/en/regexp.reference.php:
"The definition of letters and digits is controlled by PCRE's character tables, and may vary if locale-specific matching is taking place. For example, in the "fr" (French) locale, some character codes greater than 128 are used for accented letters, and these are matched by \w."

Reproduce code:
---------------
setlocale(LC_CTYPE, 'C');
var_dump(filter_var('???@example.com', FILTER_VALIDATE_EMAIL));
setlocale(LC_CTYPE, 'sv_SE');
var_dump(filter_var('???@example.com', FILTER_VALIDATE_EMAIL));

Expected result:
----------------
bool(false)
string(15) "???@example.com"

Actual result:
--------------
string(15) "???@example.com"
string(15) "???@example.com"