remote.c: introduce remote.pushdefault

This new configuration variable defines the default remote to push to,
and overrides `branch.<name>.remote` for all branches.  It is useful
in the typical triangular-workflow setup, where the remote you're
fetching from is different from the remote you're pushing to.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -727,9 +727,12 @@ branch.autosetuprebase::
 	This option defaults to never.
 
 branch.<name>.remote::
-	When in branch <name>, it tells 'git fetch' and 'git push' which
-	remote to fetch from/push to.  It defaults to `origin` if no remote is
-	configured. `origin` is also used if you are not on any branch.
+	When on branch <name>, it tells 'git fetch' and 'git push'
+	which remote to fetch from/push to.  The remote to push to
+	may be overridden with `remote.pushdefault` (for all branches).
+	If no remote is configured, or if you are not on any branch,
+	it defaults to `origin` for fetching and `remote.pushdefault`
+	for pushing.
 
 branch.<name>.merge::
 	Defines, together with branch.<name>.remote, the upstream branch
@@ -1898,6 +1901,10 @@ receive.updateserverinfo::
 	If set to true, git-receive-pack will run git-update-server-info
 	after receiving data from git-push and updating refs.
 
+remote.pushdefault::
+	The remote to push to by default.  Overrides
+	`branch.<name>.remote` for all branches.
+
 remote.<name>.url::
 	The URL of a remote repository.  See linkgit:git-fetch[1] or
 	linkgit:git-push[1].

remote.c

@@ -389,9 +389,16 @@ static int handle_config(const char *key, const char *value, void *cb)
 			add_instead_of(rewrite, xstrdup(value));
 		}
 	}
+
 	if (prefixcmp(key,  "remote."))
 		return 0;
 	name = key + 7;
+
+	/* Handle remote.* variables */
+	if (!strcmp(name, "pushdefault"))
+		return git_config_string(&pushremote_name, key, value);
+
+	/* Handle remote.<name>.* variables */
 	if (*name == '/') {
 		warning("Config remote shorthand cannot begin with '/': %s",
 			name);

t/t5516-fetch-push.sh

@@ -497,6 +497,18 @@ test_expect_success 'push with config remote.*.push = HEAD' '
 	check_push_result testrepo $the_first_commit heads/local
 '
 
+test_expect_success 'push with remote.pushdefault' '
+	mk_test up_repo heads/master &&
+	mk_test down_repo heads/master &&
+	test_config remote.up.url up_repo &&
+	test_config remote.down.url down_repo &&
+	test_config branch.master.remote up &&
+	test_config remote.pushdefault down &&
+	git push &&
+	check_push_result up_repo $the_first_commit heads/master &&
+	check_push_result down_repo $the_commit heads/master
+'
+
 test_expect_success 'push with config remote.*.pushurl' '
 
 	mk_test testrepo heads/master &&