http: release the memory of a http pack request as well

The cleanup function is used in 4 places now and it's always safe to
free up the memory as well.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -1462,6 +1462,7 @@ void release_http_pack_request(struct http_pack_request *preq)
 	}
 	preq->slot = NULL;
 	free(preq->url);
+	free(preq);
 }
 
 int finish_http_pack_request(struct http_pack_request *preq)