[server] improve TZDatetime support by depending on logilab-database 1.15.0 including https://www.logilab.org/ticket/1485893, we can now keep the tzinfo attribute on datetime objects for TZDatetime attributes, so one knows that this is a tz-aware datetime. To easily make it work with backends that have no tz support, we keep converting tz-aware datetime objects into utc naive datetime objects before sending them to the database.

from yams.buildobjs import ComputedRelation, EntityType, RelationDefinition
from cubicweb.schema import RRQLExpression

class Subject(EntityType):
    pass

class Object(EntityType):
    pass

class relation(RelationDefinition):
    subject = 'Subject'
    object = 'Object'

class computed(ComputedRelation):
    rule = 'S relation O'
    __permissions__ = {'read': (RRQLExpression('S is ET'),)}