http.receivepack==false && authenticated => Service not enabled

Even a authenticated  user can not push when http.receivepack set to false.
when
git config http.receivepack false
svc->enabled was set to 0 not -1
so we should initialize with 0 not -1

--- http-backend.c      Thu May  5 01:16:14 2011
+++ http-backend.c   Wed May 11 09:57:52 2011

@@ -23,7 +23,7 @@

 static struct rpc_service rpc_service[] = {
       { "upload-pack", "uploadpack", 1 },
-       { "receive-pack", "receivepack", -1 },
+       { "receive-pack", "receivepack", 0 },
 };

 static struct string_list *get_parameters(void)

@@ -260,8 +260,8 @@

       if (!svc)
               forbidden("Unsupported service: '%s'", name);

-       if (svc->enabled < 0) {
               const char *user = getenv("REMOTE_USER");
+       if (!svc->enabled) {
               svc->enabled = (user && *user) ? 1 : 0;
       }
       if (!svc->enabled)