Catch interrupted poll() in terminal console

Alternative to my own PR  #8108 - catch ZMQError in run_cell, and if it's
caused by an interrupt, ignore it.

more complex, especially if we want to handle the timeout nicely as
proposed in the comments, but it's possibly also more convenient for
other users of that API. Or perhaps not - I'm not sure what makes sense
for other API consumers in this case.

Fixes gh-8105

IPython/terminal/console/interactiveshell.py

@@ -8,6 +8,7 b' from __future__ import print_function'
 
 import base64
 import bdb
+import errno
 import signal
 import os
 import sys
@@ -21,6 +22,8 b' try:'
 except ImportError:
     from Queue import Empty  # Py 2
 
+from zmq import ZMQError
+
 from IPython.core import page
 from IPython.core import release
 from IPython.terminal.console.zmqhistory import ZMQHistoryManager
@@ -169,6 +172,10 b' class ZMQTerminalInteractiveShell(TerminalInteractiveShell):'
             except Empty:
                 # display intermediate print statements, etc.
                 self.handle_iopub(msg_id)
+            except ZMQError as e:
+                # Carry on if polling was interrupted by a signal
+                if e.errno != errno.EINTR:
+                    raise
         
         # after all of that is done, wait for the execute reply
         while self.client.is_alive():