read().splitlines() -> readlines()

splitlines() does not work as what we expect here for bert-base-chinese because there is a '\u2028' (unicode line seperator) token in vocab file. Value of '\u2028'.splitlines() is ['', ''].
Perhaps we should use readlines() instead.

pytorch_transformers/tokenization_bert.py

@@ -67,10 +67,9 @@ def load_vocab(vocab_file):
     """Loads a vocabulary file into a dictionary."""
     vocab = collections.OrderedDict()
     with open(vocab_file, "r", encoding="utf-8") as reader:
-        tokens = reader.read().splitlines()
+        tokens = reader.readlines()
     for index, token in enumerate(tokens):
         vocab[token] = index
-        index += 1
     return vocab