The [~TFEncoderDecoderModel.from_pretrained] currently doesn't support initializing the model from a
pytorch checkpoint. Passing from_pt=True to this method will throw an exception. If there are only pytorch
checkpoints for a particular encoder-decoder model, a workaround is:
```python
a workaround to load from pytorch checkpoint
_model = EncoderDecoderModel.from_pretrained("patrickvonplaten/bert2bert-cnn_dailymail-fp16")
_model.encoder.save_pretrained("./encoder")
_model.decoder.save_pretrained("./decoder")
model = TFEncoderDecoderModel.from_encoder_decoder_pretrained(
...     "./encoder", "./decoder", encoder_from_pt=True, decoder_from_pt=True
... )
This is only for copying some specific attributes of this particular model.
model.config = _model.config
```
This model was contributed by thomwolf. This model's TensorFlow and Flax versions
