The `add_space_before_punct_symbol` is only for TransfoXL
Author: LysandreJik
Pull request: yes

Same fix as in the [pipelines](https://github.com/huggingface/transformers/blob/master/src/transformers/pipelines.py#L626). Not the cleanest way to do a per-model change, but is bug-free for v3.0.2.

closes https://github.com/huggingface/transformers/issues/5525

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=h1) Report
> Merging [#5549](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/1bbc28bee719120f3b6f73dbe7dfe6f67e2e9fa7&el=desc) will **decrease** coverage by `0.19%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5549/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #5549      +/-   ##
==========================================
- Coverage   76.79%   76.60%   -0.20%     
==========================================
  Files         141      141              
  Lines       24634    24634              
==========================================
- Hits        18917    18870      -47     
- Misses       5717     5764      +47     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_tf\_electra.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9lbGVjdHJhLnB5) | `26.92% <0.00%> (-68.47%)` | :arrow_down: |
| [src/transformers/tokenization\_auto.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90b2tlbml6YXRpb25fYXV0by5weQ==) | `95.55% <0.00%> (-2.23%)` | :arrow_down: |
| [src/transformers/configuration\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9jb25maWd1cmF0aW9uX3V0aWxzLnB5) | `95.68% <0.00%> (-0.72%)` | :arrow_down: |
| [src/transformers/file\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9maWxlX3V0aWxzLnB5) | `79.26% <0.00%> (-0.34%)` | :arrow_down: |
| [src/transformers/generation\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9nZW5lcmF0aW9uX3RmX3V0aWxzLnB5) | `86.46% <0.00%> (+0.50%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_distilbert.py](https://codecov.io/gh/huggingface/transformers/pull/5549/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9kaXN0aWxiZXJ0LnB5) | `98.76% <0.00%> (+32.51%)` | :arrow_up: |

------

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> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=footer). Last update [1bbc28b...3d1ac81](https://codecov.io/gh/huggingface/transformers/pull/5549?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).