Problem with CMUHumanoidPositionControlledV2020 on GoToTarget task #192

dm_control/locomotion/walkers/cmu_humanoid.py contains code to support both versions (2019 & 2020) of the CMU humanoid. But the initial z position of 0.94, specified by _UPRIGHT_POS on line 174, only works for the older humanoid. When selecting the 2020 humanoid on the GoToTarget task, the feet end up well below floor level, which catapults the humanoid upwards and terminates the episode. Changing this value from 0.94 to 1.143 solves the problem for 2020.

Should there be separate versions of _UPRIGHT_POS for the two CMU humanoids? Or are there other reasons that CMUHumanoidPositionControlledV2020 won't work on the GoToTarget task?