Description:
------------
When a non-UTF-8 message is passed to the thrown exception, and exception is unhandled, the resulting output of the internal exception handler is missing exception's information (message/backtrace).

Regression since PHP 5.4
Reproducible with at least CLI, FCGI and FPM SAPI's, on Debian and Windows.
Ref: https://3v4l.org/Ah2XP

Test script:
---------------
<?php
ini_set('display_errors', 1);
ini_set('html_errors', 1);
ini_set('default_charset', "Windows-1251");
throw new Exception("\xF2\xE5\xF1\xF2"); // "тест"

Expected result:
----------------
<br />
<b>Fatal error</b>:  Uncaught exception 'Exception' with message 'тест' in /path/file:5
Stack trace:
#0 {main}
  thrown in <b>/path/file</b> on line <b>5</b><br />

Process exited with code 255.

Actual result:
--------------
<br />
<b>Fatal error</b>:   in <b>/path/file</b> on line <b>5</b><br />

Process exited with code 255.