Industrial robot simulator doesn't fail when sent multiple trajectories

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What steps will reproduce the problem?
1. Send multiple joint trajectories to /joint_path_command (this is the raw 
topic that the simulator listens to)  
2. The simulator performs the first trajectory followed by the second.  If the 
same trajectory is sent, the robot should move (instantaneously) to the start 
position and repeat the motion.

The simulator should complain about receiving a new trajectory before the last 
one has finished.  NOTE: The next higher level joint trajectory action catches 
this condition (or is supposed to), but just in case the lower level 
simulator/driver node should as well.

The problem is due to a blocking(like) segment in the trajectory call back ( 
https://code.google.com/p/swri-ros-pkg/source/browse/trunk/industrial_core/indus
trial_robot_simulator/industrial_robot_simulator#286 ).  The default motion 
controller does not buffer points, and the resulting behavior is that the 
callback blocks until the entire motion has executed.

Original issue reported on code.google.com by shaun.ed...@gmail.com on 31 Mar 2013 at 10:01