stat_tracking_info(): clear object flags used during counting

When left-right traversal counts the commits in a diverged history, it
leaves the flags in the commits smudged, and we need to clear them before
we return.  Otherwise the caller cannot inspect other branches with this
function again.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6040-tracking-info.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+test_description='remote tracking stats'
+
+. ./test-lib.sh
+
+advance () {
+	echo "$1" >"$1" &&
+	git add "$1" &&
+	test_tick &&
+	git commit -m "$1"
+}
+
+test_expect_success setup '
+	for i in a b c;
+	do
+		advance $i || break
+	done &&
+	git clone . test &&
+	(
+		cd test &&
+		git checkout -b b1 origin &&
+		git reset --hard HEAD^ &&
+		advance d &&
+		git checkout -b b2 origin &&
+		git reset --hard b1 &&
+		git checkout -b b3 origin &&
+		git reset --hard HEAD^ &&
+		git checkout -b b4 origin &&
+		advance e &&
+		advance f
+	)
+'
+
+script='s/^..\(b.\)[	 0-9a-f]*\[\([^]]*\)\].*/\1 \2/p'
+cat >expect <<\EOF
+b1 ahead 1, behind 1
+b2 ahead 1, behind 1
+b3 behind 1
+b4 ahead 2
+EOF
+
+test_expect_success 'branch -v' '
+	(
+		cd test &&
+		git branch -v
+	) |
+	sed -n -e "$script" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'checkout' '
+	(
+		cd test && git checkout b1
+	) >actual &&
+	grep -e "have 1 and 1 different" actual
+'
+
+test_expect_success 'status' '
+	(
+		cd test &&
+		git checkout b1 >/dev/null &&
+		# reports nothing to commit
+		test_must_fail git status
+	) >actual &&
+	grep -e "have 1 and 1 different" actual
+'
+
+
+test_done