[cwctl] on upgrade, clear instance_md5_version cache
The generate-static-datadir depends on a correct
config.instance_md5_version(), and we just invalidated it by
upgrading the instance.
.. _appobject_module:
:mod:`cubicweb.appobject`
=========================
.. automodule:: cubicweb.appobject
.. autoclass:: AppObject
:show-inheritance:
:members: