bug#30921: Jupyter uses the wrong Python.

[Fis Trivial]

When running jupyter, it seems that the python in "/usr/bin/python"
instead of the one in store is used. Here is the complete logging of
jupyter console output, notice those line in the middle, where displaying:
"/usr/bin/python: No module named ipykernel_launcher"

--
/gnu/store/k2y0d2rp57pnl90lxqgs5i7ywywrn456-python-traitlets-4.2.0/lib/python3.6/site-packages/traitlets/config/configurable.py:74:
 RuntimeWarning: Passing unrecoginized arguments to 
super(ConfigManager).__init__(config_dir='/home/fis/.jupyter/nbconfig').
object.__init__() takes no parameters
This error will be raised in a future release of traitlets.
  super(Configurable, self).__init__(**kwargs)
[I 14:48:57.236 NotebookApp] Serving notebooks from local directory: 
/home/fis/Others/git-repos/machine-learning/AIMA/aima-python
[I 14:48:57.237 NotebookApp] 0 active kernels 
[I 14:48:57.237 NotebookApp] The Jupyter Notebook is running at: 
http://localhost:8888/
[I 14:48:57.237 NotebookApp] Use Control-C to stop this server and shut down 
all kernels (twice to skip confirmation).
[W 14:49:11.606 NotebookApp] Notebook mdp.ipynb is not trusted
[W 14:49:11.638 NotebookApp] 404 GET 
/nbextensions/widgets/notebook/js/extension.js?v=20180324144856 (::1) 5.27ms 
referer=http://localhost:8888/notebooks/mdp.ipynb
[W 14:49:11.919 NotebookApp] Deprecated files/ URL: files/images/mdp-a.png
[I 14:49:11.920 NotebookApp] 302 GET /notebooks/files/images/mdp-a.png (::1) 
1.02ms
[I 14:49:12.687 NotebookApp] 302 GET /notebooks/images/grid_mdp.jpg (::1) 0.90ms
[I 14:49:12.689 NotebookApp] 302 GET /notebooks/images/grid_mdp_agent.jpg (::1) 
0.88ms
[I 14:49:12.955 NotebookApp] 302 GET /notebooks/images/-0.04.jpg (::1) 0.87ms
[I 14:49:13.023 NotebookApp] 302 GET /notebooks/images/-0.4.jpg (::1) 0.89ms
[I 14:49:13.124 NotebookApp] 302 GET /notebooks/images/-4.jpg (::1) 0.89ms
[I 14:49:13.210 NotebookApp] 302 GET /notebooks/images/4.jpg (::1) 0.91ms
[I 14:49:13.264 NotebookApp] 302 GET /notebooks/images/ge0.jpg (::1) 0.89ms
[I 14:49:13.265 NotebookApp] 302 GET /notebooks/images/ge1.jpg (::1) 0.80ms
[I 14:49:13.266 NotebookApp] 302 GET /notebooks/images/ge4.jpg (::1) 0.77ms
[I 14:49:13.267 NotebookApp] 302 GET /notebooks/images/ge2.jpg (::1) 0.77ms
[I 14:49:13.298 NotebookApp] Kernel started: 
9d5e4be9-15e1-488d-b1a2-408c229eb83c
/usr/bin/python: No module named ipykernel_launcher
[W 14:49:13.386 NotebookApp] 404 GET 
/static/components/MathJax/jax/element/mml/optable/BasicLatin.js?rev=2.6.0 
(::1) 1.79ms referer=http://localhost:8888/notebooks/mdp.ipynb
[I 14:49:16.299 NotebookApp] KernelRestarter: restarting kernel (1/5)
/usr/bin/python: No module named ipykernel_launcher
[I 14:49:19.305 NotebookApp] KernelRestarter: restarting kernel (2/5)
/usr/bin/python: No module named ipykernel_launcher
[I 14:49:22.314 NotebookApp] KernelRestarter: restarting kernel (3/5)
/usr/bin/python: No module named ipykernel_launcher
[W 14:49:23.474 NotebookApp] Timeout waiting for kernel_info reply from 
9d5e4be9-15e1-488d-b1a2-408c229eb83c
[I 14:49:25.324 NotebookApp] KernelRestarter: restarting kernel (4/5)
WARNING:root:kernel 9d5e4be9-15e1-488d-b1a2-408c229eb83c restarted
/usr/bin/python: No module named ipykernel_launcher
[W 14:49:28.337 NotebookApp] KernelRestarter: restart failed
[W 14:49:28.337 NotebookApp] Kernel 9d5e4be9-15e1-488d-b1a2-408c229eb83c died, 
removing from map.
ERROR:root:kernel 9d5e4be9-15e1-488d-b1a2-408c229eb83c restarted failed!
[W 14:49:28.359 NotebookApp] Kernel deleted before session
[W 14:49:28.360 NotebookApp] 410 DELETE 
/api/sessions/d6e551c2-84d2-4de4-bb25-1db37e4763c4 (::1) 1.22ms 
referer=http://localhost:8888/notebooks/mdp.ipynb
--


I'm currently running guix on top of fedora 27 x86_64, for guix version:
$ guix --version

guix (GNU Guix) 282e48eae92b1988fc7fddbf206030ccf1623728
Copyright (C) 2018 the Guix authors
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.