Merge pull request #2582 from takluyver/i2581

Fix displaying history when output cache is disabled.

Previously, disabling the output cache disabled all history. These were separated, but the %hist magic was left with an unnecessary check, where if the output cache was disabled, it would refuse to work.

Closes gh-2581

IPython/core/magics/history.py

@@ -121,10 +121,6 @@ def history(self, parameter_s = ''):
 
         """
 
-        if not self.shell.displayhook.do_full_cache:
-            print('This feature is only available if numbered prompts '
-                  'are in use.')
-            return
         args = parse_argstring(self.history, parameter_s)
 
         # For brevity