Change double quotes to single quotes in message

Most of the time when we give branch name in the message, we quote it
inside a pair of single-quotes.  git-checkout uses double-quotes; this
patch corrects the inconsistency.

Signed-off-by: Jari Aalto <jari.aalto@cante.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7201-co.sh

@@ -171,7 +171,7 @@ test_expect_success 'checkout to detach HEAD' '
 	git checkout -f renamer && git clean -f &&
 	git checkout renamer^ 2>messages &&
 	(cat >messages.expect <<EOF
-Note: moving to "renamer^" which isn'"'"'t a local branch
+Note: moving to '\''renamer^'\'' which isn'\''t a local branch
 If you want to create a new branch from this checkout, you may do so
 (now or later) by using -b with the checkout command again. Example:
   git checkout -b <new_branch_name>