[Melodic] Spam of TF Exception errors due to frames starting with '/'

[btalb]

This is caused by the issue described in this pull request: ros-simulation/stage_ros#40

We use a multi-robot Stage simulator to produce our simulated tags in the world, and the above bug is reflecting that the Stage wrapper incorrectly gives frames a starting / prefix. Previous versions of ROS / TF have been more forgiving with this error, but the versions in Melodic now spam that error. The software still appears to work (which to me means it shouldn't be an error as nothing has gone wrong... but I'll leave that alone...).

The linked pull request is open & has not been merged into the repository, let alone integrated into the ROS build farm. I would not expect to see it in apt anytime soon. If you wish to get rid of the errors there are two options:

• Manually check out a version of stage_ros with the fixes & add that to your Catkin workspace so that it overrides the version provided by apt
• Write intermediary nodes that receive the data pumped out by stage_ros, & republish without the erroneous frame names (the laser with frame /guiabot/base_laser_link is the main issue)

Let me know if you have any issues / find a better solution for now.