Description:
------------
HTTP extension or cURL library uses bad authentication credentials while reusing connection.

Requested behavior:
1) Request page from local NTLM-authenticated website
2) Then request page from internet over NTLM-authenticated proxy

Actually, second request fails. Instead of sending ?Proxy-Authorization: NTLM ?? header, library sends out ?Authorization: NTLM ?? header and ?Proxy-Authorization: Basic ?? header.

This is quite bad, because PHP tries to authenticate using Basic authorization to the proxy using passed credentials in step (2) and also tries to authenticate on target server using same credentials and NTLM method.

Reproduce code:
---------------
<?

// Configuration for first request
$r1_url = 'http://site.with.ntlm.authentication.com/';
$r1_meth = HttpRequest::METH_GET;
$r1_opts = array(
	'httpauth' => 'DOMAIN\\user:pass',
	'httpauthtype' => HTTP_AUTH_NTLM,
);

// Configuration for second request
$r2_url = 'http://www.php.net/';
$r2_meth = HttpRequest::METH_GET;
$r2_opts = array(
	'proxytype' => HTTP_PROXY_HTTP,
	'proxyhost' => 'proxyserver.with.ntlm.authentication',
	'proxyport' => 80,
	'proxyauth' => 'DOMAIN\\user:pass',
	'proxyauthtype' => HTTP_AUTH_NTLM,
);

// Send request 1 to server with NTLM authentication
$r1 = new HttpRequest($r1_url, $r1_meth, $r1_opts);
try {
	$r1->send();
} catch (HttpException $e) {}

// Expect to echo "200"
echo $r1->getResponseCode()."\r\n";

// Send request 2 to server over proxy with PROXY NTLM authentication
$r2 = new HttpRequest($r2_url, $r2_meth, $r2_opts);
try {
	$r2->send();
} catch (HttpException $e) {}

// Expect to echo "200"
echo $r2->getResponseCode()."\r\n";

?>

Expected result:
----------------
// I expect to see two times successfull HTTP result

200
200

// Expected HTTP communication (authorization headers) for the requests
(1) C&#8594;S: GET / HTTP/1.1
         Authorization: NTLM ? (first auth. header)
         ?
    S&#8594;C: HTTP/1.1 401 Unauthorized
         WWW-Authenticate: NTLM ? (second auth. header)
         ?

    C&#8594;S: GET / HTTP/1.1
         Authorization: NTLM ? (final auth. header)
    S&#8594;C: HTTP/1.1 200 OK
         ?

(2) C&#8594;S: GET http://www.php.net/ HTTP/1.1
         Proxy-Authorization: NTLM ? (first auth. header)
         ?
    S&#8594;C: HTTP/1.1 401 Unauthorized
         Proxy-Authenticate: NTLM ? (second auth. header)
         ?

    C&#8594;S: GET http://www.php.net/ HTTP/1.1
         Proxy-Authorization: NTLM ? (final auth. header)
    S&#8594;C: HTTP/1.1 200 OK
         ?

Actual result:
--------------
// However, second connection fails telling
// 407 Proxy Authentication Required

200
407

// Actual HTTP communication (authorization headers) for the requests
(1) C&#8594;S: GET / HTTP/1.1
         Authorization: NTLM ? (first auth. header)
         ?
    S&#8594;C: HTTP/1.1 401 Unauthorized
         WWW-Authenticate: NTLM ? (second auth. header)
         ?

    C&#8594;S: GET / HTTP/1.1
         Authorization: NTLM ? (final auth. header)
    S&#8594;C: HTTP/1.1 200 OK
         ?

(2) C&#8594;S: GET http://www.php.net/ HTTP/1.1
         Proxy-Authorization: Basic ? (BAD BAD BAD!)
         Authorization: NTLM ? (BAD BAD BAD!)
         ?
    S&#8594;C: HTTP/1.1 407 Proxy Authentication Required
         Proxy-Authenticate: NTLM