Connection handling functions doesn't works with Apache 2.0.39
Problem was same with php 4.2.1 and Apache 2.0.36
Here is a script that write a tmp trace file..
Anytime, connection look like "NORMAL" (0 code) and detection of a connection abort is impossible...
    - pjluc

<?
$old=ignore_user_abort(false);
$now=ignore_user_abort();
register_shutdown_function("end_of_script");

print "Start...($old,$now)<br>";
sleep(2);
phpinfo();
sleep(2);
print "...End<br>";

function end_of_script(){

  $line="Status=[".connection_status()."][".connection_aborted()."]\n";
  $out=fopen("/tmp/foo.txt","a");
  fwrite($out,$line);
  fclose($out);
}

?>