[tf contrib seq2seq] Bugfixes to BeamSearchDecoder

Implementation by Cinjon Resnick.  He can't push this since he's traveling.
I just copied the fix and added some small syntax tweaks to make the unit
tests pass.  More comprehensive unit tests will come in the near future.

Fixes at least part of #9904.

BeamSearchDecoder:
1. Fix the bug where we don't pass the next cell state through.
2. Gather the cell state (and attention if that's a part of the model
   as an AttentionWrapper on the cell) according to the next_beam_ids.
PiperOrigin-RevId: 157415564

0 files changed, 0 insertions, 0 deletions