Figure out potential duplication in ConfigStore about metaseq

[suchenzang]

Some more notes from pdb-ing :

# before hydra_init():

(Pdb) cs.repo.keys()
dict_keys(['hydra', '_dummy_empty_config_.yaml'])

# after hydra_init():

(Pdb) cs.repo.keys()
dict_keys(['hydra', '_dummy_empty_config_.yaml', 'base_config.yaml', '_name.yaml', 'common.yaml', 'common_eval.yaml', 'distributed_training.yaml', 'dataset.yaml', 'optimization.yaml', 'checkpoint.yaml', 'generation.yaml', 'eval_lm.yaml', 'model.yaml', 'task.yaml', 'criterion.yaml', 'optimizer.yaml', 'lr_scheduler.yaml', 'bpe.yaml', 'tokenizer.yaml'])

# after import fairseq.models

(Pdb) cs.repo.keys()
dict_keys(['hydra', '_dummy_empty_config_.yaml', 'base_config.yaml', '_name.yaml', 'common.yaml', 'common_eval.yaml', 'distributed_training.yaml', 'dataset.yaml', 'optimization.yaml', 'checkpoint.yaml', 'generation.yaml', 'eval_lm.yaml', 'model.yaml', 'task.yaml', 'criterion.yaml', 'optimizer.yaml', 'lr_scheduler.yaml', 'bpe.yaml', 'tokenizer.yaml', 'model'])

(Pdb) cs.repo['model'].keys()
dict_keys(['transformer_lm.yaml'])