Storm should use "IS NULL" when comparing against a Variable with a None value

[Marc Tardif]

When Storm compares against a Variable with a None value, like IntVariable(None), this results in the SQL query: = NULL. Instead, this should result in: IS NULL. The same applies when comparing for equality and non-equality.

[Gustavo Niemeyer (niemeyer)]

I don't think this is true:

>>> from storm.locals import *
>>> from storm.expr import compile
>>> class C(object):
... __storm_table__ = "C"
... column = Int(primary=True)
...
>>> compile(C.column == None)
'C."column" IS NULL'

Can you please provide another example where this is the case?

[Marc Tardif (cr3)]

I've been unable to reproduce the context in which I was comparing a column to a Variable type with a None value, as opposed to comparing a column to None directly which worked fine. So, I'll also consider this bug as invalid.