CI Failed on test_prototype_builtin_datasets.py

[YosuaMichael]

Test are starting to fail on test_prototype_builtin_datasets.py on 24 June 2022
Here are an example:
https://github.com/pytorch/vision/runs/7041792653?check_suite_focus=true

__________________ TestCommon.test_transformable[mnist-train] __________________
Traceback (most recent call last):
  File "/home/runner/work/vision/vision/test/test_prototype_builtin_datasets.py", line 102, in test_transformable
    next(iter(dataset.map(transforms.Identity())))
  File "/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/utils/data/datapipes/datapipe.py", line 135, in class_function
    result_pipe = cls(source_dp, *args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/utils/data/datapipes/iter/callable.py", line 80, in __init__
    validate_input_col(fn, input_col)
  File "/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/utils/data/datapipes/utils/common.py", line 43, in validate_input_col
    f"The function {fn.__name__} takes {len(non_default_params)} "
  File "/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/nn/modules/module.py", line 1225, in __getattr__
    type(self).__name__, name))
AttributeError: 'Identity' object has no attribute '__name__'

As mentioned by @datumbox , if we check the error trace it indicate the call on validate_input_col(fn, input_col) and this function is introduced on pytorch/pytorch#79344 , so for now this PR is the likely reason for the breakage.

cc @seemethere @bjuncek @pmeier @NicolasHug since this is about prototype dataset, can you also take a look on this?

Update:

• There is a fix on pytorch: Raise warning for unpickable local function pytorch#80140 (will confirm on next nightlies)
• It is now fixed (2022-06-27)

[datumbox]

It's possible that pytorch/pytorch#79344 made the change.

@ejguan @NivekT Would you be able to check?

[NivekT]

There should be a fix in this PR, it should be part of the next nightly build.
https://github.com/pytorch/pytorch/pull/80140/files#diff-3c24d6216b32a33b711fb755d5b9a14f21a9ace7167749cd4c3ef02c5baa4912

cc: @ejguan

[ejguan]

I have reverted the culprit PR pytorch/pytorch#79344 since I found more issues with it. The Ci should be back to green in the next nightly release.
Thank you for reporting it.

[YosuaMichael]

I have confirmed that now the CI is green again with #5009. Thanks @ejguan for the fix!