Description:
------------
sapi_cli_ub_write() is faulty and may go into a tight infinite loop under certain circumstances. If write() produces an error, it calls php_handle_aborted_connection(), but if ignore_user_abort(true) has been called, this does not exit the request. Thus it enters an infinite loop.

Bug #20053 is a similar bug in a different SAPI. It's likely that many SAPIs have copied this code and suffer the same problem.

Reproduce code:
---------------
<?php
ignore_user_abort(true);
while ( true ) {
	fwrite( STDERR, microtime(true) . "\n" );
	echo "Hello\n";
	usleep(500000);
}
?>

Run it like this:

$ php nfs-test.php > /mnt/some-nfs-mount/test-file

Then while that is running, on another server:

$ rm /mnt/some-nfs-mount/test-file



Expected result:
----------------
It should exit when the file is removed, like it does when ignore_user_abort(true) is not called.

Actual result:
--------------
After a few seconds, the stderr output will stop ticking, and strace will show a flood of:

write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)