Moveit - Executed path doesn't match the planned path

edit

Screencast of the problem: https://youtu.be/rINMG6N6iNE

As you can see in the video, the path executed by the (simulated robot) does not match the planned path. The desired path has an Orientation Constraint using the Move Group Python Interface described in the question/issue here: How to use orientation constraints in moveit? There is no real robot or gazebo connected, the joint_states are simply published by the joint_state_publisher. (fake joint states)

Procedure: (summary)

self.add_tilt_constaint()
destination_pose = self.robot_controller.move_group.get_current_pose()
destination_pose.pose.position.y -= 1.0
self.move_group.set_pose_target(destination_pose)
plan = self.move_group.plan()
self.move_group.execute(plan)

The used planner is RRT.

Any ideas what the cause of the problem could be?

I'm using Kinetic on Ubuntu GNOME 16.04