I see.
BTW, some other test files like test_cpp_extensions.py seems to be outdated. It outputs errors like
======================================================================
ERROR: test_backward (__main__.TestCppExtension)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_cpp_extensions.py", line 72, in test_backward
    mm = cpp_extension.MatrixMultiplier(4, 8)
NameError: name 'cpp_extension' is not defined

======================================================================
ERROR: test_cuda_extension (__main__.TestCppExtension)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_cpp_extensions.py", line 113, in test_cuda_extension
    import torch_test_cpp_extension.cuda as cuda_extension
ModuleNotFoundError: No module named 'torch_test_cpp_extension'

I guess the sub-directory cpp_extension has been changed to cpp_extensions recently.
Thank you