After deleting a model from the world via the gazebo inteface then saving the world file the next time the world is used it generates the following error. A residue defintion remain in the state vector for the world. The rrbot was deleted but is stilled in the state vector.

Error [World.cc:1650] Unable to find model[rrbot]

    <state>
      <model name='rrbot'>
        <pose>-7 -8 0 0 -0 0</pose>
        <link name='base_link'>
          <pose>-7 -8 0.1 0 -0 0</pose>
          <velocity>0 0 0 0 -0 0</velocity>
          <acceleration>0 0 0 0 -0 0</acceleration>
          <wrench>0 0 0 0 -0 0</wrench>
        </link>
        <link name='left_wheel'>
          <pose>-6.85 -8.13 0.1 0 1.5707 1.5707</pose>
          <velocity>0 0 0 0 -0 0</velocity>
          <acceleration>0 0 0 0 -0 0</acceleration>
          <wrench>0 0 0 0 -0 0</wrench>
        </link>
        <link name='right_wheel'>
          <pose>-6.85 -7.87 0.1 0 1.5707 1.5707</pose>
          <velocity>0 0 0 0 -0 0</velocity>
          <acceleration>0 0 0 0 -0 0</acceleration>
          <wrench>0 0 0 0 -0 0</wrench>
        </link>
      </model>
    </state>