branch.autosetupmerge: allow boolean values, or "all"

Junio noticed that switching on autosetupmerge unilaterally started
cluttering the config for local branches.  That is not the original
intention of branch.autosetupmerge, which was meant purely for
convenience when branching off of remote branches, but that semantics
got lost somewhere.

If you still want that "new" behavior, you can switch
branch.autosetupmerge to the value "all".  Otherwise, it is interpreted
as a boolean, which triggers setting up defaults _only_ when branching
off of a remote branch, i.e. the originally intended behavior.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -309,7 +309,10 @@ branch.autosetupmerge::
 	so that gitlink:git-pull[1] will appropriately merge from that
 	remote branch.  Note that even if this option is not set,
 	this behavior can be chosen per-branch using the `--track`
-	and `--no-track` options.  This option defaults to false.
+	and `--no-track` options.  This option can have values
+	'false' (never touch the configuration), 'all' (do this
+	for all branches), or 'true' (do this only when
+	branching from a remote tracking branch), and defaults to 'true'.
 
 branch.<name>.remote::
 	When in branch <name>, it tells `git fetch` which remote to fetch.

Documentation/git-checkout.txt

@@ -52,8 +52,9 @@ OPTIONS
 	set up configuration so that git-pull will automatically
 	retrieve data from the remote branch.  Set the
 	branch.autosetupmerge configuration variable to true if you
-	want git-checkout and git-branch to always behave as if
-	'--track' were given.
+	want git-checkout and git-branch to behave as if
+	'--track' were given when you branch from a remote
+	tracking branch.
 
 --no-track::
 	When -b is given and a branch is created off a remote branch,

builtin-branch.c

@@ -22,7 +22,7 @@ static const char builtin_branch_usage[] =
 static const char *head;
 static unsigned char head_sha1[20];
 
-static int branch_track_remotes = 1;
+static int branch_track = 1; /* 0 = none, 1 = remotes, 2 = all */
 
 static int branch_use_color;
 static char branch_colors[][COLOR_MAXLEN] = {
@@ -66,8 +66,12 @@ static int git_branch_config(const char *var, const char *value)
 		color_parse(value, var, branch_colors[slot]);
 		return 0;
 	}
-	if (!strcmp(var, "branch.autosetupmerge"))
-		branch_track_remotes = git_config_bool(var, value);
+	if (!strcmp(var, "branch.autosetupmerge")) {
+		if (!strcmp(value, "all"))
+			branch_track = 2;
+		else
+			branch_track = git_config_bool(var, value);
+	}
 
 	return git_default_config(var, value);
 }
@@ -504,7 +508,9 @@ static void create_branch(const char *name, const char *start_name,
 	/* When branching off a remote branch, set up so that git-pull
 	   automatically merges from there.  So far, this is only done for
 	   remotes registered via .git/config.  */
-	if (real_ref && track)
+	if (real_ref && (track == 2 ||
+				(track == 1 &&
+				 !prefixcmp(real_ref, "refs/remotes/"))))
 		set_branch_defaults(name, real_ref);
 
 	if (write_ref_sha1(lock, sha1, msg) < 0)
@@ -564,7 +570,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	int i;
 
 	git_config(git_branch_config);
-	track = branch_track_remotes;
+	track = branch_track;
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -576,7 +582,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			break;
 		}
 		if (!strcmp(arg, "--track")) {
-			track = 1;
+			track = 2;
 			continue;
 		}
 		if (!strcmp(arg, "--no-track")) {

t/t3200-branch.sh

@@ -148,6 +148,15 @@ test_expect_success 'test tracking setup via config' \
      test $(git config branch.my3.remote) = local &&
      test $(git config branch.my3.merge) = refs/heads/master'
 
+test_expect_success 'autosetupmerge = all' '
+	git config branch.autosetupmerge true &&
+	git branch all1 master &&
+	test -z "$(git config branch.all1.merge)" &&
+	git config branch.autosetupmerge all &&
+	git branch all2 master &&
+	test $(git config branch.all2.merge) = refs/heads/master
+'
+
 test_expect_success 'test overriding tracking setup via --no-track' \
     'git config branch.autosetupmerge true &&
      git config remote.local.url . &&