Fix a problem twice named with ros namespace.

[shun818]

Occured problem:

I insert gazebo_ros_imu_sensor plugin my robot.

<plugin filename="libgazebo_ros_imu_sensor.so" name="imu_plugin">
  <robotNamespace>robotNamespace</robotNamespace>
  <topicName>imu</topicName>
  ...
</plugin>

and launch file is

<node pkg="gazebo_ros" type="spawn_model" name="spawn_robot" args="
  -urdf
  ...
  -robot_namespace robotNamespace
</node>

then, gazebo was published ROS topic is named /robotNamespace/robotNamespace/imu

[chapulina]

The fix looks correct to me, but we shouldn't merge this into melodic because it would break existing users. Would you mind targeting this PR at noetic-devel?

It would also be nice to add a more verbose commit message about this, which will go into the changelog, so users migrating from melodic to noetic can quickly find out how to migrate their code.

Thanks!

[shun818]

No problem. However, I am not familiar with the operation of Github. Can you change this PR target?