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/t9107-git-svn-migrate.sh

@@ -6,14 +6,14 @@ test_description='git svn metadata migrations from previous versions'
 test_expect_success 'setup old-looking metadata' '
 	cp "$GIT_DIR"/config "$GIT_DIR"/config-old-git-svn &&
 	mkdir import &&
-	cd import &&
+	(cd import &&
 		for i in trunk branches/a branches/b \
 		         tags/0.1 tags/0.2 tags/0.3; do
 			mkdir -p $i && \
 			echo hello >> $i/README || exit 1
 		done && \
 		svn_cmd import -m test . "$svnrepo"
-		cd .. &&
+		) &&
 	git svn init "$svnrepo" &&
 	git svn fetch &&
 	rm -rf "$GIT_DIR"/svn &&