Fix hang-upon exit in terminal version, which was due to the history autosave thread not exiting.

IPython/core/history.py

@@ -255,7 +255,8 b' class HistoryManager(object):'
 
 class HistorySaveThread(threading.Thread):
     """Thread to save history periodically"""
-
+    daemon = True
+    
     def __init__(self, IPython_object, time_interval, exit_now):
         threading.Thread.__init__(self)
         self.IPython_object = IPython_object
@@ -273,6 +274,12 b' class HistorySaveThread(threading.Thread):'
             #printing for debug
             #print("Saving...")
             self.IPython_object.save_history()
+            
+    def stop(self):
+        self.exit_now=True
+        self.cond.acquire()
+        self.cond.notify()
+        self.cond.release()
 
 def magic_history(self, parameter_s = ''):
     """Print input history (_i<n> variables), with most recent last.

IPython/frontend/terminal/interactiveshell.py

@@ -499,10 +499,6 b' class TerminalInteractiveShell(InteractiveShell):'
         This method calls the ask_exit callback."""
         if self.confirm_exit:
             if self.ask_yes_no('Do you really want to exit ([y]/n)?','y'):
-                self.shell.history_thread.exit_now=True
-                self.shell.history_thread.cond.acquire()
-                self.shell.history_thread.cond.notify()
-                self.shell.history_thread.cond.release()
                 self.ask_exit()
         else:
             self.ask_exit()