Fix bugs when readline is absent (pdb and quitting would crash badly)

https://bugs.launchpad.net/ipython/+bug/495173

IPython/core/iplib.py

@@ -1450,6 +1450,8 b' class InteractiveShell(Component, Magic):'
 
     def set_completer_frame(self, frame=None):
         """Set the frame of the completer."""
+        if not self.has_readline:
+            return
         if frame:
             self.Completer.namespace = frame.f_locals
             self.Completer.global_namespace = frame.f_globals
@@ -1842,7 +1844,8 b' class InteractiveShell(Component, Magic):'
             except EOFError:
                 if self.autoindent:
                     self.rl_do_indent = False
-                    self.readline_startup_hook(None)
+                    if self.has_readline:
+                        self.readline_startup_hook(None)
                 self.write('\n')
                 self.exit()
             except bdb.BdbQuit: