Combining a list of elements containing only the monoid's unit should return the
unit.
Since the unit is skipped, it would return an empty domain instead of the unit,
meaning that (0, '=', 1) could not be used in a group rule.
To test this, create a record rule on a model M with domain (0, '=', 1)
that applies to group G.
Log in with a user in group G and access model M; you can read everything
(provided no other record rule applies) whereas you should see nothing.
Because of expression.AND(global_domains + [expression.OR(group_domains)])
we want the empty domain to still be left untouched, even if it violates
the OR's unit rules (i.e. OR(empty, OR(R)) = OR(R) <=> OR(empty) = unit).
Meaning that no group rule would reduce to having a (0, '=' 1) group rule.
So in the end we don't really care about all that algebraic nonsense.
closesodoo/odoo#28765
len-odoo
e5486c12bc