Reset possible helper before reusing remote structure

If one had multiple URLs configured for remote with previous one
having forced helper but the subsequent one not, like:

url = foo::bar://baz
url = ssh://example/example.git

Then the subsequent URL is passed to foo helper, which isn't
correct. Fix it to be parsed normally by resetting foreign VCS
name before parsing the URL protocol.

Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport.c

@@ -875,6 +875,9 @@ struct transport *transport_get(struct remote *remote, const char *url)
 		url = remote->url[0];
 	ret->url = url;
 
+	/* In case previous URL had helper forced, reset it. */
+	remote->foreign_vcs = NULL;
+
 	/* maybe it is a foreign URL? */
 	if (url) {
 		const char *p = url;