updates per review

a few more notebook mentions in docstrings,
and inappropriate use of setdefault.

IPython/html/services/contents/filemanager.py

@@ -309,10 +309,10 b' class FileContentsManager(ContentsManager):'
         """Save the file model and return the model with no content."""
         path = path.strip('/')
 
-        if 'content' not in model:
-            raise web.HTTPError(400, u'No file content provided')
         if 'type' not in model:
             raise web.HTTPError(400, u'No file type provided')
+        if 'content' not in model and model['type'] != 'directory':
+            raise web.HTTPError(400, u'No file content provided')
 
         # One checkpoint should always exist
         if self.file_exists(name, path) and not self.list_checkpoints(name, path):

IPython/html/services/contents/manager.py

@@ -165,16 +165,16 b' class ContentsManager(LoggingConfigurable):'
         path = path.strip('/')
         if model is None:
             model = {}
-        if 'content' not in model:
+        if 'content' not in model and model.get('type', None) != 'directory':
             if ext == '.ipynb':
                 metadata = current.new_metadata(name=u'')
                 model['content'] = current.new_notebook(metadata=metadata)
-                model.setdefault('type', 'notebook')
-                model.setdefault('format', 'json')
+                model['type'] = 'notebook'
+                model['format'] = 'json'
             else:
                 model['content'] = ''
-                model.setdefault('type', 'file')
-                model.setdefault('format', 'text')
+                model['type'] = 'file'
+                model['format'] = 'text'
         if 'name' not in model:
             model['name'] = self.increment_filename('Untitled' + ext, path)
 
@@ -185,7 +185,7 b' class ContentsManager(LoggingConfigurable):'
     def copy(self, from_name, to_name=None, path=''):
         """Copy an existing file and return its new model.
 
-        If to_name not specified, increment `from_name-Copy#.ipynb`.
+        If to_name not specified, increment `from_name-Copy#.ext`.
         """
         path = path.strip('/')
         model = self.get_model(from_name, path)