Variance-based acceptance only works correctly for rules that match all inputs

[heidmic]

suprb/suprb/optimizer/rule/acceptance.py

Line 27 in 2af0421

class Variance(RuleAcceptance):

@dpaetzel says: if mean(local_y) == 0, then this is a 1/beta–weighted variance, however, this assumption is wrong for non-general rules