A lot of methods are designed to work with pure datetime objects as args. If
the value comes from the database it will be rounded at the level of seconds
(0 microsecond). If it comes from a call do datetime.now() / datetime.utcnow()
the datetime object has a value != 0 for its mircroseconds attribute. Therefore
some methods have unpredictable results depending of the origin of the values
manipulated since the microsecond argument is missing into all the calls to
datetime.replace
Closes#15768
Due to an error introduced when migrating the module at new API
at commit a4e57ea16c limited attendances
having date_from and / or date_to were not correctly taken into
account.
Tests have been added to avoid regression.
Laurent Mignon (ACSONE)