in irunner, don't send last newline if child is gone

fixes an issue where irunner could send last newline after child exits, raising an OSError

IPython/lib/irunner.py

@@ -263,6 +263,7 b' class InteractiveRunner(object):'
 
         # Leave the child ready for more input later on, otherwise select just
         # hangs on the second invocation.
+        if c.isalive():
         c.send('\n')
         
         # Return any requested output