catch NotImplementedError, not NotImplemented

in _ipython_display_

IPython/core/display.py

@@ -115,9 +115,15 b' def display(*objs, **kwargs):'
 
     for obj in objs:
 
-        # If _ipython_display_ is defined, use that to display this object.  If
-        # it returns NotImplemented, use the _repr_ logic (default).
-        if not hasattr(obj, '_ipython_display_') or obj._ipython_display_(**kwargs) is NotImplemented:
+        # If _ipython_display_ is defined, use that to display this object.
+        display_method = getattr(obj, '_ipython_display_', None)
+        if display_method is not None:
+            try:
+                display_method(**kwargs)
+            except NotImplementedError:
+                pass
+            else:
+                continue
             if raw:
                 publish_display_data('display', obj, metadata)
             else:            

IPython/core/displayhook.py

@@ -241,9 +241,14 b' class DisplayHook(Configurable):'
         """
         self.check_for_underscore()
         if result is not None and not self.quiet():
-            # If _ipython_display_ is defined, use that to display this object.  If
-            # it returns NotImplemented, use the _repr_ logic (default).
-            if not hasattr(result, '_ipython_display_') or result._ipython_display_() is NotImplemented:
+            # If _ipython_display_ is defined, use that to display this object.
+            display_method = getattr(result, '_ipython_display_', None)
+            if display_method is not None:
+                try:
+                    return display_method()
+                except NotImplementedError:
+                    pass
+            
                 self.start_displayhook()
                 self.write_output_prompt()
                 format_dict, md_dict = self.compute_format_data(result)