lalinference_pipe fails when computing ROQ weights in ligo-py37 environment

lalinference_pipe fails with code StopIteration() when running with ROQ waveforms during the compute_roq_weights command:

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/cvmfs/ligo-containers.opensciencegrid.org/lscsoft/conda/latest/envs/ligo-py37/bin/lalinference_pipe", line 483, in <module>
    for this_cp in setup_roq(cp):
RuntimeError: generator raised StopIteration

The current fix is to source the ligo-py36 environment, but this seems like it should only be a short-term solution.