counterpoint to the "take all checks out of `compile`" movement:

Invalidated 238 targets.
F401:ERROR   tests/python/pants_test/base_test.py:021 'BuildConfiguration' imported but unused
     |from pants.build_graph.build_configuration import BuildConfiguration

F401:ERROR   tests/python/pants_test/base_test.py:022 'BuildFileAddressMapper' imported but unused
     |from pants.build_graph.build_file_address_mapper import BuildFileAddressMapper

F401:ERROR   tests/python/pants_test/base_test.py:024 'BuildFileParser' imported but unused
     |from pants.build_graph.build_file_parser import BuildFileParser

F401:ERROR   tests/python/pants_test/base_test.py:025 'MutableBuildGraph' imported but unused
     |from pants.build_graph.mutable_build_graph import MutableBuildGraph

F821:ERROR   tests/python/pants_test/base_test.py:268-274 undefined name 'EngineInitializer'
     |    graph_helper = EngineInitializer.setup_legacy_graph(
     |        self.pants_ignore_patterns,
     |        self.pants_workdir,
     |        build_ignore_patterns=self.build_ignore_patterns,
     |        exclude_target_regexps=None,
     |        subproject_roots=None,
     |      )

F821:ERROR   tests/python/pants_test/base_test.py:277 undefined name 'LiteralTargetRoots'
     |        LiteralTargetRoots([]),


FAILURE: 6 Python Style issues found. For import order related issues, please try `./pants fmt.isort <targets>`


17:27:14 00:17   [complete]
               FAILURE