status: ignore status.aheadbehind in porcelain formats

Teach porcelain V[12] formats to ignore the status.aheadbehind
config setting. They only respect the --[no-]ahead-behind
command line argument.  This is for backwards compatibility
with existing scripts.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>

Author: jeffhostetler

Documentation/config/status.txt

@@ -15,8 +15,7 @@ status.branch::
 status.aheadBehind::
 	EXPERIMENTAL, Set to true to enable --ahead-behind and false to
 	enable --no-ahead-behind by default in linkgit:git-status[1] for
-	all status formats.  Defaults to true.  Changing this may
-	break backwards compatibility for existing scripts.
+	non-porcelain status formats.  Defaults to true.
 
 status.displayCommentPrefix::
 	If set to true, linkgit:git-status[1] will insert a comment

builtin/commit.c

@@ -1157,11 +1157,13 @@ static void finalize_deferred_config(struct wt_status *s)
 
 	/*
 	 * If the user did not give a "--[no]-ahead-behind" command
-	 * line argument, then we inherit the a/b config setting.
-	 * If is not set, then we inherit _FULL for backwards
-	 * compatibility.
+	 * line argument *AND* we will print in a human-readable format
+	 * (short, long etc.) then we inherit from the status.aheadbehind
+	 * config setting.  In all other cases (and porcelain V[12] formats
+	 * in particular), we inherit _FULL for backwards compatibility.
 	 */
-	if (s->ahead_behind_flags == AHEAD_BEHIND_UNSPECIFIED)
+	if (use_deferred_config &&
+	    s->ahead_behind_flags == AHEAD_BEHIND_UNSPECIFIED)
 		s->ahead_behind_flags = status_deferred_config.ahead_behind;
 
 	if (s->ahead_behind_flags == AHEAD_BEHIND_UNSPECIFIED)

t/t7064-wtstatus-pv2.sh

@@ -436,10 +436,6 @@ test_expect_success 'verify --[no-]ahead-behind with V2 format' '
 		git status --no-ahead-behind --porcelain=v2 --branch --untracked-files=all >actual &&
 		test_cmp expect actual &&
 
-		# Confirmat that "status.aheadbehind" works on V2 format.
-		git -c status.aheadbehind=false status --porcelain=v2 --branch --untracked-files=all >actual &&
-		test_cmp expect actual &&
-
 		# Confirm --ahead-behind reports traditional branch.ab with 1/0.
 		cat >expect <<-EOF &&
 		# branch.oid $HUF
@@ -449,6 +445,14 @@ test_expect_success 'verify --[no-]ahead-behind with V2 format' '
 		EOF
 
 		git status --ahead-behind --porcelain=v2 --branch --untracked-files=all >actual &&
+		test_cmp expect actual &&
+
+		# Confirm that "status.aheadbehind" DOES NOT work on V2 format.
+		git -c status.aheadbehind=false status --porcelain=v2 --branch --untracked-files=all >actual &&
+		test_cmp expect actual &&
+
+		# Confirm that "status.aheadbehind" DOES NOT work on V2 format.
+		git -c status.aheadbehind=true status --porcelain=v2 --branch --untracked-files=all >actual &&
 		test_cmp expect actual
 	)
 '