OpenWebText: NonMatchingSplitsSizesError
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) ?
## 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

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
 
 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) ?