When SystemEvent_SERVICE_CLEANUP_CLOSE_INACTIVE_ARTIFACTS called, changesets are done as anonymous (getCurrentUser()) instead of Tracker_Workflow_WorkflowUser because no user argument given in userCanUpdate() so it's considered null by default.

Changes:
* Tracker_Artifact_Changeset_NewChangesetCreator::saveNewChangesetForField add user to $field->userCanUpdate($submitter)

* Method interface signature Workflow_Transition_Condition::validate and retrieve current_user as fourth argument and delete his instanciation inside of Workflow_Transition_Condition_Permissions::validate.