data files are optional now

--HG--
branch : trunk
diff --git a/jinja2/loaders.py b/jinja2/loaders.py
index 8b21fdc..74dee5e 100644
--- a/jinja2/loaders.py
+++ b/jinja2/loaders.py
@@ -23,7 +23,7 @@
            or (path.altsep and path.altsep in piece) or \
            piece == path.pardir:
             raise TemplateNotFound(template)
-        elif piece != '.':
+        elif piece and piece != '.':
             pieces.append(piece)
     return pieces