httpclient: no proxy creds in requests if proxy is CONNECT type

src/transports/httpclient.c

@@ -681,6 +681,11 @@ static int generate_connect_request(
 	return git_buf_oom(buf) ? -1 : 0;
 }
 
+static bool use_connect_proxy(git_http_client *client)
+{
+    return client->proxy.url.host && !strcmp(client->server.url.scheme, "https");
+}
+
 static int generate_request(
 	git_http_client *client,
 	git_http_request *request)
@@ -734,7 +739,8 @@ static int generate_request(
 		git_buf_printf(buf, "Expect: 100-continue\r\n");
 
 	if ((error = apply_server_credentials(buf, client, request)) < 0 ||
-	    (error = apply_proxy_credentials(buf, client, request)) < 0)
+	    (!use_connect_proxy(client) &&
+			(error = apply_proxy_credentials(buf, client, request)) < 0))
 		return error;
 
 	if (request->custom_headers) {
@@ -1027,8 +1033,7 @@ static int http_client_connect(
 	reset_parser(client);
 
 	/* Reconnect to the proxy if necessary. */
-	use_proxy = client->proxy.url.host &&
-	            !strcmp(client->server.url.scheme, "https");
+	use_proxy = use_connect_proxy(client);
 
 	if (use_proxy) {
 		if (!client->proxy_connected || !client->keepalive ||