@abstractmethod
  @contextmanager
  def mk_project_tree(self, build_root_src):
    pass
Trailing spaces in expected output are significant:
dataset/ETHPy150Open pantsbuild/pants/tests/python/pants_test/engine/exp/test_fs.py/FSTestBase.mk_project_tree--crossover with--dataset/ETHPy150Open babble/babble/include/jython/Lib/test/test_doctest.py/test_trailing_space_in_test