ipapi.get now returns None if there are no InteractiveShells running.

It used to simply raise an IndexError, which was bad.

IPython/core/ipapi.py

@@ -1,35 +1,38 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 This module is *completely* deprecated and should no longer be used for
 any purpose.  Currently, we have a few parts of the core that have
 not been componentized and thus, still rely on this module.  When everything
 has been made into a component, this module will be sent to deathrow.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
-from IPython.core.error import TryNext, UsageError
+from IPython.core.error import TryNext, UsageError, IPythonCoreError
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
+
 def get():
     """Get the most recently created InteractiveShell instance."""
     from IPython.core.iplib import InteractiveShell
     insts = InteractiveShell.get_instances()
+    if len(insts)==0:
+        return None
     most_recent = insts[0]
     for inst in insts[1:]:
         if inst.created > most_recent.created:
             most_recent = inst
     return most_recent