Title: `blog_authorship_corpus` is broken
Author: fdtomasi (NONE)
State: closed
Created: 2021-10-15T09:20:40Z
Labels: bug

## Describe the bug
The dataset `blog_authorship_corpus` is broken.
By bypassing the checksum checks, the loading does not return any error but the resulting dataset is empty.
I suspect it is because the data download url is broken (http://www.cs.biu.ac.il/~koppel/blogs/blogs.zip).

## Steps to reproduce the bug
```python
from datasets import load_dataset
ds = load_dataset("blog_authorship_corpus", split="train", download_mode='force_redownload')
```

## Expected results
No error.

## Actual results
```
---------------------------------------------------------------------------
NonMatchingChecksumError                  Traceback (most recent call last)
/tmp/ipykernel_5237/1729238701.py in <module>
      2 ds = load_dataset(
      3     "blog_authorship_corpus", split="train",
----> 4     download_mode='force_redownload'
      5 )

/opt/conda/lib/python3.7/site-packages/datasets/load.py in load_dataset(path, name, data_dir, data_files, split, cache_dir, features, download_config, download_mode, ignore_verifications, keep_in_memory, save_infos, script_version, use_auth_token, task, streaming, **config_kwargs)
   1115         ignore_verifications=ignore_verifications,
   1116         try_from_hf_gcs=try_from_hf_gcs,
-> 1117         use_auth_token=use_auth_token,
   1118     )
   1119 

/opt/conda/lib/python3.7/site-packages/datasets/builder.py in download_and_prepare(self, download_config, download_mode, ignore_verifications, try_from_hf_gcs, dl_manager, base_path, use_auth_token, **download_and_prepare_kwargs)
    635                     if not downloaded_from_gcs:
    636                         self._download_and_prepare(
--> 637                             dl_manager=dl_manager, verify_infos=verify_infos, **download_and_prepare_kwargs
    638                         )
    639                     # Sync info

/opt/conda/lib/python3.7/site-packages/datasets/builder.py in _download_and_prepare(self, dl_manager, verify_infos, **prepare_split_kwargs)
    707         if verify_infos:
    708             verify_checksums(
--> 709                 self.info.download_checksums, dl_manager.get_recorded_sizes_checksums(), "dataset source files"
    710             )
    711 

/opt/conda/lib/python3.7/site-packages/datasets/utils/info_utils.py in verify_checksums(expected_checksums, recorded_checksums, verification_name)
     38     if len(bad_urls) > 0:
     39         error_msg = "Checksums didn't match" + for_verification_name + ":\n"
---> 40         raise NonMatchingChecksumError(error_msg + str(bad_urls))
     41     logger.info("All the checksums matched successfully" + for_verification_name)
     42 

NonMatchingChecksumError: Checksums didn't match for dataset source files:
['http://www.cs.biu.ac.il/~koppel/blogs/blogs.zip']
```

## Environment info
- `datasets` version: 1.13.2
- Platform: Linux-4.19.0-18-cloud-amd64-x86_64-with-debian-10.11
- Python version: 3.7.10
- PyArrow version: 5.0.0

Comments:
Hi @fdtomasi, thanks for reporting.

You are right: the original host data URL does no longer exist.

I've contacted the authors of the dataset to ask them if they host this dataset in another URL.

Hi, @fdtomasi, the URL is fixed.

The fix is already in our master branch and it will be accessible in our next release.

In the meantime, you can include the fix if you install the `datasets` library from the master branch:
```
pip install -U git+ssh://git@github.com/huggingface/datasets.git@master#egg=datasest
```
or
```
pip install -U git+https://github.com/huggingface/datasets.git@master#egg=datasets
```

Awesome thank you so much for the quick fix!