push: respect --no-thin

- From the beginning of push.c in 755225d, 2006-04-29, "thin" option
  was enabled by default but could be turned off with --no-thin.

- Then Shawn changed the default to 0 in favor of saving server
  resources in a4503a1, 2007-09-09. --no-thin worked great.

- One day later, in 9b28851 Daniel extracted some code from push.c to
  create transport.c. He (probably accidentally) flipped the default
  value from 0 to 1 in transport_get().

From then on --no-thin is effectively no-op because git-push still
expects the default value to be false and only calls
transport_set_option() when "thin" variable in push.c is true (which
is unnecessary). Correct the code to respect --no-thin by calling
transport_set_option() in both cases.

receive-pack learns about --reject-thin-pack-for-testing option,
which only is for testing purposes, hence no document update.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/push.c b/builtin/push.c
index 04f0eaf..333a1fb 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -15,7 +15,7 @@
 	NULL,
 };
 
-static int thin;
+static int thin = 1;
 static int deleterefs;
 static const char *receivepack;
 static int verbosity;
@@ -313,8 +313,7 @@
 	if (receivepack)
 		transport_set_option(transport,
 				     TRANS_OPT_RECEIVEPACK, receivepack);
-	if (thin)
-		transport_set_option(transport, TRANS_OPT_THIN, "yes");
+	transport_set_option(transport, TRANS_OPT_THIN, thin ? "yes" : NULL);
 
 	if (verbosity > 0)
 		fprintf(stderr, _("Pushing to %s\n"), transport->url);