[server] fix unittest_security for py3k
- use source.binary_to_str instead of str(), helps when the backend
returns memoryviews
- fixup str vs bytes
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'),)}