pyqt5 python3.5.5 pip : impossible d'installer la bonne doc

Bonjour
j'essaye de faire fonctionner correctement les exemples fourni avec les sources de pytqt5.
J'utilise: python 3.5.5 mon os est Debian 8 (j'ai donc recompiler le deb à partir des sources) j'ai bien installe pyqt5 et qtdemo fonctionne sauf qu'il ne fait pas le lien avec la doc:

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(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip search pyqtdoc
PyQtdoc (5.5.1)  - PyQtdoc installs Qt documentation for PyQt
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip3.5 install PyQtdoc==5.5.1
Collecting PyQtdoc==5.5.1
  Could not find a version that satisfies the requirement PyQtdoc==5.5.1 (from versions: 4.8.4, 4.8.7)
No matching distribution found for PyQtdoc==5.5.1
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip3.5 search pyqtdoc
PyQtdoc (5.5.1)  - PyQtdoc installs Qt documentation for PyQt
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip3.5 install PyQtdoc
Collecting PyQtdoc
  Downloading https://files.pythonhosted.org/packages/87/62/596f40886d81b321460e2f8bfa3f7ff4d7f5fb76e7d2fcc74e48a48c05e90/PyQtdoc-4.8.7.zip (57.7MB)
    100% |████████████████████████████████| 57.7MB 1.2MB/s 
Installing collected packages: PyQtdoc
  Running setup.py install for PyQtdoc ... done
Successfully installed PyQtdoc-4.8.7
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ 
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip freeze
PyQt5==5.10.1
PyQtdoc==4.8.7
sip==4.19.8
yolk3k==0.9
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ pip -V
pip 10.0.0 from /home/user/Documents/pythonQt5QML2/lib/python3.5/site-packages/pip (python 3.5)
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ python -V
Python 3.5.5
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ 
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ 
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ cat /etc/de
debconf.conf    debian_version  default/        deluser.conf    depmod.d/       
(pythonQt5QML2) user@debian:~/Documents/tmp/PyQt5_gpl-5.10.2.dev1804151313/examples/qtdemo$ cat /etc/debian_version 
8.10

J'ai le message d'erreur dans qtdemo.py:
"Could not load description. Ensure that the documentation for Qt is built."
et quand je demande à voir la Documentation en cliquant sur le bouton de Documentation, j'ai une pop-up qui s'affiche en me disant:
"Could not start /home/user/Documents/pythonQt5QML2/lib/python3.5/site-packages/PyQt5/Qt/bin/assistant."

Merci bien