Description:
------------
Then writing session and closing session (include session_write_close function), processing is continued without finishing the exit() call back.
A funnier problem occurs when I use this problem with an exception. 
When at first I carry out session_write_close() calling exit, an exception object becomes null by the later exception handling of an exception.

Reproduce code:
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<?php

session_set_save_handler('dummy', 'dummy', 'dummy','write', 'dummy', 'dummy');

function dummy(){}

function write() {
       print "Write.\n";
       exit;
       print "Not come to here.\n";
}

session_start();

session_write_close();

print "I'm here.\n";


Expected result:
----------------
Write.


Actual result:
--------------
Write.
I'm here.