DEV: Remove unnecessary notary calls.

IPython/html/services/contents/manager.py

@@ -498,7 +498,6 b' class ContentsManager(LoggingConfigurable):'
         """Create a checkpoint."""
 
         nb = nbformat.from_dict(self.get(path, content=True)['content'])
-        self.check_and_sign(nb, path)
         return self.checkpoint_manager.create_checkpoint(nb, path)
 
     def list_checkpoints(self, path):
@@ -513,8 +512,6 b' class ContentsManager(LoggingConfigurable):'
             path,
         )
 
-        self.mark_trusted_cells(nb, path)
-
         model = {
             'content': nb,
             'type': 'notebook',