Several tests: cd inside subshell instead of around

Fixed all places where it was a straightforward change from cd'ing into a
directory and back via "cd .." to a cd inside a subshell.

Found these places with "git grep -w "cd \.\.".

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9115-git-svn-dcommit-funky-renames.sh

@@ -61,11 +61,11 @@ test_expect_success 'add a file with plus signs' '
 
 test_expect_success 'clone the repository to test rebase' '
 	git svn clone "$svnrepo" test-rebase &&
-	cd test-rebase &&
+	(cd test-rebase &&
 		echo test-rebase > test-rebase &&
 		git add test-rebase &&
-		git commit -m test-rebase &&
-		cd ..
+		git commit -m test-rebase
+		)
 	'
 
 test_expect_success 'make a commit to test rebase' '