protect kernelapp/qtconsole from invalid connection files

(clean error/exit, rather than crash)

also use stdlib json to load connection file, not zmq.jsonapi, which can be
jsonlib2, which will return Longs, causing TraitError.

IPython/frontend/qt/console/qtconsoleapp.py

@@ -17,6 +17,7 b' Authors:'
 #-----------------------------------------------------------------------------
 
 # stdlib imports
+import json
 import os
 import signal
 import sys
@@ -24,7 +25,6 b' import sys'
 # System library imports
 from IPython.external.qt import QtGui
 from pygments.styles import get_all_styles
-from zmq.utils import jsonapi as json
 
 # Local imports
 from IPython.config.application import boolean_flag
@@ -373,7 +373,11 b' class IPythonQtConsoleApp(BaseIPythonApplication):'
         # should load_connection_file only be used for existing?
         # as it is now, this allows reusing ports if an existing
         # file is requested
+        try:
         self.load_connection_file()
+        except Exception:
+            self.log.error("Failed to load connection file: %r", self.connection_file, exc_info=True)
+            self.exit(1)
     
     def load_connection_file(self):
         """load ip/port/hmac config from JSON connection file"""

IPython/zmq/kernelapp.py

@@ -16,12 +16,12 b' Authors'
 #-----------------------------------------------------------------------------
 
 # Standard library imports.
+import json
 import os
 import sys
 
 # System library imports.
 import zmq
-from zmq.utils import jsonapi as json
 
 # IPython imports.
 from IPython.core.ultratb import FormattedTB
@@ -192,8 +192,11 b' class KernelApp(BaseIPythonApplication):'
     def init_connection_file(self):
         if not self.connection_file:
             self.connection_file = "kernel-%s.json"%os.getpid()
-        
+        try:
         self.load_connection_file()
+        except Exception:
+            self.log.error("Failed to load connection file: %r", self.connection_file, exc_info=True)
+            self.exit(1)
     
     def init_sockets(self):
         # Create a context, a session, and the kernel sockets.