Anyone have any idea why this might be happening on master?

$ ./pants goals
Bootstrapping pants_deps with requirements:
  /Users/tansy/code/pants/3rdparty/python/requirements.txt
  /Users/tansy/code/pants/3rdparty/python/twitter/commons/requirements.txt
  /Users/tansy/code/pants/pants-plugins/3rdparty/python/requirements.txt

Failed to create venv.