[web/staticcontrollers] create a unique temporary file for concat handling
Predictable names means different processes can race against each other.
Let's avoid that and use mkstemp to get a real unique temporary file,
and atomically rename it when we're done.
Closes #3524182
from yams.buildobjs import RelationDefinition
class ARelation(RelationDefinition):
subject = 'CWUser'
object = 'CWGroup'