Fix bug where output prompts were coming *after* output values.

This means that on exit/quit, we'll see something, so I added a simple 'bye'
to those.  Not pretty, but easier than messing with the prompt logic.

IPython/core/prompts.py

@@ -533,20 +533,6 b' class CachedOutput:'
             except KeyError:
                 pass
         if arg is not None:
-
-            # and now call a possibly user-defined print mechanism
-            try:
-                manipulated_val = self.display(arg)
-            except TypeError:
-                # If the user's display hook didn't return a string we can
-                # print, we're done.  Happens commonly if they return None
-                return
-            
-            # user display hooks can change the variable to be stored in
-            # output history
-            if manipulated_val is not None:
-                arg = manipulated_val
-                
             cout_write = Term.cout.write # fast lookup
             # first handle the cache and counters
 
@@ -566,6 +552,22 b' class CachedOutput:'
             else:
                 print "self.do_full_cache = False"
 
+            # and now call a possibly user-defined print mechanism. Note that
+            # self.display typically prints as a side-effect, we don't do any
+            # printing to stdout here.
+            try:
+                manipulated_val = self.display(arg)
+            except TypeError:
+                # If the user's display hook didn't return a string we can
+                # print, we're done.  Happens commonly if they return None
+                cout_write('\n')
+                return
+            
+            # user display hooks can change the variable to be stored in
+            # output history
+            if manipulated_val is not None:
+                arg = manipulated_val
+
             # avoid recursive reference when displaying _oh/Out
             if arg is not self.user_ns['_oh']:
                 self.update(arg)

IPython/core/quitter.py

@@ -36,5 +36,6 b' class Quitter(object):'
 
     def __call__(self):
         self.shell.ask_exit()
+        return 'Bye.'
 
     __repr__ = __call__