Maybe you should read how the "bug" was resolved? It wasn't really bug in PHP itself but just missing documentation.

Sorry, I did more tests and it's still no right.
The documentation says: "Calling restore_error_handler() from the error_handler function is ignored."
This is bugged for 5.0.4 and is not true for 5.1.0RC1

The follow code works as I expect in 5.1.0RC1 on windows.
But on 5.0.4 restore_error_handler is ignored inside error_handler, but calling restore_error_handler outside, will exec twice, as if the restore_error_handler was pushed on a stack.

<pre>
<?

function error_handler1() {
	echo "\n[".__FUNCTION__."]\n";
}

function error_handler2() {
	echo "\n[".__FUNCTION__."]\n";
}

function error_handler3() {
	echo "\n[".__FUNCTION__."]\n";
//	restore_error_handler();
}

function error_handler4() {
	echo "\n[".__FUNCTION__."]\n";
	restore_error_handler();
}

set_error_handler('error_handler1');
set_error_handler('error_handler2');
set_error_handler('error_handler3');
set_error_handler('error_handler4');

echo foo;
echo bar;

restore_error_handler();

echo test;

?>

RESULT FOR 5.0.4
[error_handler4]
foo
[error_handler4]
bar
[error_handler1]
test

if the restore_error_handler is really ignored inside error handler, the result should be:
[error_handler4]
foo
[error_handler4]
bar
[error_handler3]
test

RESULT FOR 5.1.0RC1
[error_handler4]
foo
[error_handler3]
bar
[error_handler1]
test

it seens that restore_error_handler is not ignored inside handler on 5.1.0RC1

If it's fixed in 5.1, it's fixed. If it's not fixed in 5.0.4, too bad.