Fix data download of wmt14

test=develop

python/paddle/dataset/wmt16.py

@@ -71,15 +71,16 @@ def __build_dict(tar_file, dict_size, save_path, lang):
             for w in sen.split():
                 word_dict[w] += 1
 
-    with open(save_path, "w") as fout:
-        fout.write("%s\n%s\n%s\n" % (START_MARK, END_MARK, UNK_MARK))
+    with open(save_path, "wb") as fout:
+        fout.write(
+            cpt.to_bytes("%s\n%s\n%s\n" % (START_MARK, END_MARK, UNK_MARK)))
         for idx, word in enumerate(
                 sorted(
                     six.iteritems(word_dict), key=lambda x: x[1],
                     reverse=True)):
             if idx + 3 == dict_size: break
-            fout.write(word[0].encode('utf-8'))
-            fout.write('\n')
+            fout.write(cpt.to_bytes(word[0]))
+            fout.write(cpt.to_bytes('\n'))
 
 
 def __load_dict(tar_file, dict_size, lang, reverse=False):