[Python-modules-team] Bug#875538: jupyter-nbextension-jupyter-js-widgets: reproduced on first jupyter install

[r.ductor]

Package: jupyter-nbextension-jupyter-js-widgets
Followup-For: Bug #875538

Dear Maintainer,

I do not use widgets but I report the bug hoping this might help.

First install of jupyter bundle. I've got this warning:

Setting up jupyter-nbextension-jupyter-js-widgets (6.0.0-2) ...
/usr/lib/python3.6/runpy.py:125: RuntimeWarning: 'notebook.nbextensions' found in sys.modules after import of p
ackage 'notebook', but prior to execution of 'notebook.nbextensions'; this may result in unpredictable behaviou
r
  warn(RuntimeWarning(msg))
Enabling notebook extension jupyter-js-widgets/extension...
      - Validating: OK
Setting up python3-ipywidgets (6.0.0-2) ...
Processing triggers for libc-bin (2.26-4) ...

More info:

root at EliteBook:~# ls -al /etc/jupyter/nbconfig/*.json
-rw-r--r-- 1 root root  3 Feb 11 18:19 /etc/jupyter/nbconfig/common.json
-rw-r--r-- 1 root root  3 Feb 11 18:19 /etc/jupyter/nbconfig/edit.json
-rw-r--r-- 1 root root 71 Feb 11 18:19 /etc/jupyter/nbconfig/notebook.json
-rw-r--r-- 1 root root  3 Feb 11 18:19 /etc/jupyter/nbconfig/terminal.json
-rw-r--r-- 1 root root  3 Feb 11 18:19 /etc/jupyter/nbconfig/tree.json
root at EliteBook:~# cat /etc/jupyter/nbconfig/common.json
{}
root at EliteBook:~# cat /etc/jupyter/nbconfig/edit.json
{}
root at EliteBook:~# cat /etc/jupyter/nbconfig/notebook.json
{
  "load_extensions": {
    "jupyter-js-widgets/extension": true
  }
}root at EliteBook:~# cat /etc/jupyter/nbconfig/terminal.json
{}
root at EliteBook:~# cat /etc/jupyter/nbconfig/tree.json
{}
root at EliteBook:~#



-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (900, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.14.0-3-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages jupyter-nbextension-jupyter-js-widgets depends on:
ii  python            2.7.14-4
ii  python3           3.6.4-1
ii  python3-notebook  5.2.2-1

jupyter-nbextension-jupyter-js-widgets recommends no packages.

Versions of packages jupyter-nbextension-jupyter-js-widgets suggests:
pn  python-ipywidgets   <none>
ii  python3-ipywidgets  6.0.0-2

-- no debconf information