t6040 test: stop using global "script" variable

Change test code added in c0234b2ef6 ("stat_tracking_info(): clear
object flags used during counting", 2008-07-03) to stop using the
"script" variable also used for lazy prerequisites in
test-lib-functions.sh.

Since this test uses test_i18ncmp and expects to use its own "script"
variable twice it implicitly depends on the C_LOCALE_OUTPUT
prerequisite not being a lazy prerequisite. A follow-up change will
make it a lazy prerequisite, so we must remove this landmine before
inadvertently stepping on it as we make that change.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6040-tracking-info.sh

@@ -38,7 +38,7 @@ test_expect_success setup '
 	advance h
 '
 
-script='s/^..\(b.\) *[0-9a-f]* \(.*\)$/\1 \2/p'
+t6040_script='s/^..\(b.\) *[0-9a-f]* \(.*\)$/\1 \2/p'
 cat >expect <<\EOF
 b1 [ahead 1, behind 1] d
 b2 [ahead 1, behind 1] d
@@ -53,7 +53,7 @@ test_expect_success 'branch -v' '
 		cd test &&
 		git branch -v
 	) |
-	sed -n -e "$script" >actual &&
+	sed -n -e "$t6040_script" >actual &&
 	test_i18ncmp expect actual
 '
 
@@ -71,7 +71,7 @@ test_expect_success 'branch -vv' '
 		cd test &&
 		git branch -vv
 	) |
-	sed -n -e "$script" >actual &&
+	sed -n -e "$t6040_script" >actual &&
 	test_i18ncmp expect actual
 '