OpenWebText: NonMatchingSplitsSizesError
## Describe the bug

When downloading `openwebtext`, I'm getting:
```
datasets.utils.info_utils.NonMatchingSplitsSizesError: [{'expected': SplitInfo(name='train', num_bytes=39769494896, num_examples=8013769, dataset_name='openwebtext'), 'recorded': SplitInfo(name='train', num_bytes=39611023912, num_examples=7982430, dataset_name='openwebtext')}]
```

I suspect that the file we download from has changed since the size doesn't look like to match with documentation

`Downloading:   0%|          | 0.00/12.9G [00:00<?, ?B/s]` This suggest the total size is 12.9GB, whereas the one documented mentions `Size of downloaded dataset files: 12283.35 MB`.

## Steps to reproduce the bug
```python
from datasets import load_dataset

load_dataset("openwebtext", download_mode="force_redownload")
```

## Expected results

Loading is successful

## Actual results

Loading throws above error.

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 1.10.2
- Platform: linux (Redhat version 8.1)
- Python version: 3.8
- PyArrow version: 4.0.1

Thanks for reporting, I'm updating the verifications metadata I just regenerated the verifications metadata and noticed that nothing changed: the data file is fine (the checksum didn't change), and the number of examples is still 8013769. Not sure how you managed to get 7982430 examples.

Can you try to delete your cache ( by default at `~/.cache/huggingface/datasets`) and try again please ?
Also, on which platform are you (linux/macos/windows) ? I'll try without deleting the whole cache (we have large datasets already stored). I was under the impression that `download_mode="force_redownload"` would bypass cache.
Sorry plateform should be linux (Redhat version 8.1) Hi @thomasw21 , are you still having this issue after clearing your cache ? Sorry I haven't had time to work on this. I'll close and re-open if I can't figure out why I'm having this issue. Thanks for taking a look !