Remove print statements in ZMQ parent pollers.

These statements were originally inserted for debugging purposes. However, if
the parent process owns the child's stdout and the parent dies, the print
statements will deadlock, preventing the poller from terminating its process and
thereby utterly breaking it.

IPython/zmq/parentpoller.py

@@ -5,9 +5,6 b' import time'
 from thread import interrupt_main
 from threading import Thread
 
-# Local imports.
-from IPython.utils.io import raw_print
-
 
 class ParentPollerUnix(Thread):
     """ A Unix-specific daemon thread that terminates the program immediately 
@@ -24,7 +21,6 b' class ParentPollerUnix(Thread):'
         while True:
             try:
                 if os.getppid() == 1:
-                    raw_print('Killed by parent poller!')
                     os._exit(1)
                 time.sleep(1.0)
             except OSError, e:
@@ -117,9 +113,7 b' class ParentPollerWindows(Thread):'
                 handle = handles[result - WAIT_OBJECT_0]
 
                 if handle == self.interrupt_handle:
-                    raw_print('Interrupted by parent poller!')
                     interrupt_main()
 
                 elif handle == self.parent_handle:
-                    raw_print('Killed by parent poller!')
                     os._exit(1)