git-checkout: Support relative paths containing "..".

Signed-off-by: David Symonds <dsymonds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-checkout.sh

@@ -134,9 +134,9 @@ Did you intend to checkout '$@' which can not be resolved as commit?"
 	fi
 
 	# Make sure the request is about existing paths.
-	git ls-files --error-unmatch -- "$@" >/dev/null || exit
+	git ls-files --full-name --error-unmatch -- "$@" >/dev/null || exit
-	git ls-files -- "$@" |
+	git ls-files --full-name -- "$@" |
-	git checkout-index -f -u --stdin
+		(cd_to_toplevel && git checkout-index -f -u --stdin)
 
         # Run a post-checkout hook -- the HEAD does not change so the
         # current HEAD is passed in for both args