t7201: use 'git -C' to avoid subshell

Signed-off-by: NCharvi Mendiratta <charvi077@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t7201-co.sh

@@ -339,10 +339,7 @@ test_expect_success 'switch branches while in subdirectory' '
 	git checkout master &&
 
 	mkdir subs &&
-	(
-		cd subs &&
-		git checkout side
-	) &&
+	git -C subs checkout side &&
 	! test -f subs/one &&
 	rm -fr subs
 '
@@ -357,10 +354,7 @@ test_expect_success 'checkout specific path while in subdirectory' '
 
 	git checkout master &&
 	mkdir -p subs &&
-	(
-		cd subs &&
-		git checkout side -- bero
-	) &&
+	git -C subs checkout side -- bero &&
 	test -f subs/bero
 '