Merge pull request #341 from potatochip/patch-1

catch exception if pathlib not install

pytorch_pretrained_bert/file_utils.py

@@ -29,7 +29,7 @@ try:
     from pathlib import Path
     PYTORCH_PRETRAINED_BERT_CACHE = Path(os.getenv('PYTORCH_PRETRAINED_BERT_CACHE',
                                                    Path.home() / '.pytorch_pretrained_bert'))
-except AttributeError:
+except (AttributeError, ImportError):
     PYTORCH_PRETRAINED_BERT_CACHE = os.getenv('PYTORCH_PRETRAINED_BERT_CACHE',
                                               os.path.join(os.path.expanduser("~"), '.pytorch_pretrained_bert'))