Description:
------------
I parsed url with UTF-8 encoding and noticed that UTF symbol 8 ( ８ = EF BC 98 code units) replaces to EF BC 5F code units that are not correct utf symbol.

Script didn't generate errors and warnings.

Also I noticed that utf symbols from 0 (０) to 7  (７) and 9 (９) parses by parse_url() without any problems.

This bug also appears on PHP 5.2.3 and PHP 5.2.5

 

Reproduce code:
---------------
<?php
// mb_convert_encoding() provides same result as html_entity_decode() in this example
	//$url = mb_convert_encoding("https://example.com/?SHAMEI=&#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;&#65304;&#65296;&#12496;&#12531;&amp;SHAMEI_CD=01465,", "utf-8", "html-entities");
	$url = html_entity_decode("https://example.com/?SHAMEI=&#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;&#65305;&#65296;&#12496;&#12531;&amp;SHAMEI_CD=01465,",null,"utf-8");
	echo "Original URL = $url <br />\n";
	$result = parse_url($url);
	echo print_r($result);
?>

Expected result:
----------------
Original URL = https://example.com/?SHAMEI=&#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;80&#12496;&#12531;&SHAMEI_CD=01465, 

Array
(
    [scheme] => https
    [host] => example.com
    [path] => /
    [query] => SHAMEI=&#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;80&#12496;&#12531;&SHAMEI_CD=01465,
)

Actual result:
--------------
Original URL = https://example.com/?SHAMEI=&#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;80&#12496;&#12531;&SHAMEI_CD=01465,

Array
(
    [scheme] => https
    [host] => example.com
    [path] => /
    [query] => &#12521;&#12531;&#12489;&#12463;&#12523;&#12540;&#12470;&#12540;&#65533;_0&#12496;&#12531;&SHAMEI_CD=01465,