DRCSIM: SDF bug prevents roslaunch from working.

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The version of Gazebo/drcsim loaded using

sudo apt-get install drcsim

works when invoked with just

gazebo

but has the following fatal errors when invoked as

roslaunch atlas_utils atlas.launch

Error [SDF.cc:993] Unable to find value for key[link_name]
Error [SDF.cc:993] Unable to find value for key[link_name]
Exception [Joint.cc:125] Couldn't Find Parent Link[]
Error [Model.cc:153] LoadJoint Failed

These messages are repeated about 28 times. This message is at the end:

Error [SDF.cc:761] Missing element description for [link_name]
[gazebo-2] process has finished cleanly
log file: /home/cga/.ros/log/e01679e8-a55e-11e2-9de5-d4bed9fd5ae1/gazebo-2*.log

Trying to invoke our copy of the atlas urdf (the one that works with drcsim-nightly installed) with

gazebo world

has the same problem.