avoid call to redis when testing if object is a MeasurementGroup instance
When starting a scan, X calls to redis are to get active measurement group name ; this comes from
the get_all
method that tests each object from setup_globals
to build the list of MeasurementGroup
objects ; X being equal to the number of exported objects in setup_globals
.
So, fixing __class__
to return MeasurementGroup
avoids all the calls to redis when dealing with
the default measurement group object.