storage_path and storage_key have duplicate prefix

[fanlu]

@pzelasko , This is the part of exp/data/cuts_train-clean-100.json.gz generated by prepare.py, the storage_key has the prefix of storage_path

    "features": {
      "type": "fbank",
      "num_frames": 1597,
      "num_features": 40,
      "sampling_rate": 16000,
      "start": 0,
      "duration": 15.965,
      "storage_type": "lilcom_files",
      "storage_path": "exp/data/feats_train-clean-100",
      "storage_key": "exp/data/feats_train-clean-100/a39/a39aea3e-0edc-4cba-a3ef-49c49e769ec8.llc"
    }

will cause problem in train dataloader of train.py

FileNotFoundError: [Errno 2] No such file or directory: 'exp/data/feats_train-clean-100/exp/data/feats_train-clean-100/a39/a39aea3e-0edc-4cba-a3ef-49c49e769ec8.llc'

[pzelasko]

Thanks, will look into it later today.

[pzelasko]

Fixing it here lhotse-speech/lhotse#141 will release 0.2.2 later