Summary:
# Before submitting
- [X] Was this discussed/approved via a Github issue? (no need for typos, doc improvements)
- [X] Did you read the [contributor guideline](https://github.com/pytorch/fairseq/blob/main/CONTRIBUTING.md)?
- [X] Did you make sure to update the docs?
- [X] Did you write any new necessary tests?
## What does this PR do?
Fixes https://github.com/pytorch/fairseq/issues/4300
## PR review
Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.
## Did you have fun?
Big time!
Note:
I had to update `black` because of [this known issue](https://github.com/psf/black/issues/2964):
```
black....................................................................Failed
- hook id: black
- exit code: 1
Traceback (most recent call last):
File "/Users/azzhipa/.cache/pre-commit/repoxt83whf2/py_env-python3.8/bin/black", line 8, in <module>
sys.exit(patched_main())
File "/Users/azzhipa/.cache/pre-commit/repoxt83whf2/py_env-python3.8/lib/python3.8/site-packages/black/__init__.py", line 1423, in patched_main
patch_click()
File "/Users/azzhipa/.cache/pre-commit/repoxt83whf2/py_env-python3.8/lib/python3.8/site-packages/black/__init__.py", line 1409, in patch_click
from click import _unicodefun
ImportError: cannot import name '_unicodefun' from 'click' (/Users/azzhipa/.cache/pre-commit/repoxt83whf2/py_env-python3.8/lib/python3.8/site-packages/click/__init__.py)
```
Pull Request resolved: https://github.com/pytorch/fairseq/pull/4344
Reviewed By: zhengwy888
Differential Revision: D35691648
Pulled By: dianaml0
fbshipit-source-id: 4bdf408bc9d9cca76c9c08e138cf85b1d00d14d4
