ipython 3.1.0-1 archlinux bug

ipython notebook log

~ ipython notebook
Traceback (most recent call last):
  File "/bin/ipython", line 5, in <module>
    start_ipython()
  File "/usr/lib/python3.4/site-packages/IPython/__init__.py", line 120, in start_ipython
    return launch_new_instance(argv=argv, **kwargs)
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 573, in launch_instance
    app.initialize(argv)
  File "<string>", line 2, in initialize
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/lib/python3.4/site-packages/IPython/terminal/ipapp.py", line 321, in initialize
    super(TerminalIPythonApp, self).initialize(argv)
  File "<string>", line 2, in initialize
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/lib/python3.4/site-packages/IPython/core/application.py", line 369, in initialize
    self.parse_command_line(argv)
  File "/usr/lib/python3.4/site-packages/IPython/terminal/ipapp.py", line 316, in parse_command_line
    return super(TerminalIPythonApp, self).parse_command_line(argv)
  File "<string>", line 2, in parse_command_line
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 471, in parse_command_line
    return self.initialize_subcommand(subc, subargv)
  File "<string>", line 2, in initialize_subcommand
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/lib/python3.4/site-packages/IPython/config/application.py", line 402, in initialize_subcommand
    subapp = import_item(subapp)
  File "/usr/lib/python3.4/site-packages/IPython/utils/importstring.py", line 42, in import_item
    module = __import__(package, fromlist=[obj])
  File "/usr/lib/python3.4/site-packages/IPython/html/notebookapp.py", line 37, in <module>
    ioloop.install()
  File "/usr/lib/python3.4/site-packages/zmq/eventloop/ioloop.py", line 181, in install
    from tornado import ioloop
ImportError: No module named 'tornado'

pacman info

~ pacman -Qi ipython    
Name           : ipython
Version        : 3.1.0-1
Description    : An enhanced Interactive Python shell.
Architecture   : any
URL            : http://ipython.org
Licenses       : BSD
Groups         : None
Provides       : ipython3
Depends On     : python  sqlite  python-setuptools
Optional Deps  : python-nose: for IPython's test suite [installed]
                 python-pyqt4: for ipython qtconsole [installed]
                 python-sip: for ipython qtconsole [installed]
                 python-pygments: for ipython qtconsole [installed]
                 python-pyzmq: for ipython qtconsole [installed]
Required By    : accerciser
Optional For   : None
Conflicts With : None
Replaces       : ipython3
Installed Size :   9,75 MiB
Packager       : Kyle Keen <keenerd@gmail.com>
Build Date     : dim. 12 avril 2015 08:59:42 CEST
Install Date   : sam. 02 mai 2015 20:18:11 CEST
Install Reason : Installed as a dependency for another package
Install Script : No
Validated By   : Signature