Failed to eval src/python/pants/backend/jvm/subsystems:jvm_tool_mixin
Failed to eval 'file src/python/pants/backend/jvm/subsystems/jvm_tool_mixin.py':
  File "/home/travis/build/pantsbuild/pants/src/python/pants/backend/jvm/subsystems/jvm_tool_mixin.py", line 12, in <module>
    from pants.option.custom_types import target_option
  File "/home/travis/build/pantsbuild/pants/src/python/pants/option/custom_types.py", line 11, in <module>
    from pants.util.eval import parse_expression
  File "/home/travis/build/pantsbuild/pants/src/python/pants/util/eval.py", line 10, in <module>
    import six
No module named six