To test the pants options whether prints out only functioning options, I tried to make a dummy task to contain some dummy deprecated options. but so far had some trouble loading up the task as a plugin.

load_build_configuration_from_source(build_configuration, additional_backends=backends or [])
  File "/Users/yic/workspace/pants/src/python/pants/bin/extension_loader.py", line 124, in load_build_configuration_from_source
    load_backend(build_configuration, backend_package)
  File "/Users/yic/workspace/pants/src/python/pants/bin/extension_loader.py", line 142, in load_backend
    .format(backend=backend_module, error=e))

Exception message: Failed to load the pants.contrib.dummy_options.register backend: No module named dummy_options.register

even if the structures looks like this

[tw-mbp-yic pants (option_option)]$ find contrib/dummy_options/src/python/pants/contrib/dummy_options/
contrib/dummy_options/src/python/pants/contrib/dummy_options/
contrib/dummy_options/src/python/pants/contrib/dummy_options//__init__.py
contrib/dummy_options/src/python/pants/contrib/dummy_options//BUILD
contrib/dummy_options/src/python/pants/contrib/dummy_options//register.py
contrib/dummy_options/src/python/pants/contrib/dummy_options//tasks
contrib/dummy_options/src/python/pants/contrib/dummy_options//tasks/__init__.py
contrib/dummy_options/src/python/pants/contrib/dummy_options//tasks/BUILD
contrib/dummy_options/src/python/pants/contrib/dummy_options//tasks/dummy_options.py