Error on empty c.Session.key

[k00mi]

Adding c.Session.key = '' to the default (i.e. empty except for c = get_config()) ipython_config.py results in the following error when starting ipython console:

[ZMQTerminalIPythonApp] CRITICAL | Bad config encountered during initialization:
[ZMQTerminalIPythonApp] CRITICAL | The 'key' trait of a Session instance must be a string, but a value of '' <class 'str'> was specified.

I originally opened this issue on IHaskell, but it seems to be a problem with IPython itself. Some more info:

{'codename': 'Work in Progress',
 'commit_hash': b'6fcfc4d',
 'commit_source': 'repository',
 'default_encoding': 'UTF-8',
 'ipython_path': '/home/koomi/ipython/IPython',
 'ipython_version': '2.0.0-dev',
 'os_name': 'posix',
 'platform': 'Linux-3.11.5-1-ARCH-x86_64-with-arch',
 'sys_executable': '/usr/bin/python',
 'sys_platform': 'linux',
 'sys_version': '3.3.2 (default, Sep  6 2013, 09:30:10) \n[GCC 4.8.1 20130725 (prerelease)]'}

[takluyver]

It should actually be bytes, i.e. b''. That error message isn't very helpful, especially under Python 3. I'll see if I can do something about it.