Downgrade six to 1.0.0 (#4180)

python/ray/utils.py

@@ -10,6 +10,7 @@ import inspect
 import logging
 import numpy as np
 import os
+import six
 import subprocess
 import sys
 import threading
@@ -180,6 +181,37 @@ def decode(byte_str, allow_none=False):
         return byte_str
 
 
+def ensure_str(s, encoding="utf-8", errors="strict"):
+    """Coerce *s* to `str`.
+
+    To keep six with lower version, see Issue 4169, we copy this function
+    from six == 1.12.0.
+
+    TODO(yuhguo): remove this function when six >= 1.12.0.
+
+    For Python 2:
+      - `unicode` -> encoded to `str`
+      - `str` -> `str`
+
+    For Python 3:
+      - `str` -> `str`
+      - `bytes` -> decoded to `str`
+    """
+    if six.PY3:
+        text_type = str
+        binary_type = bytes
+    else:
+        text_type = unicode  # noqa: F821
+        binary_type = str
+    if not isinstance(s, (text_type, binary_type)):
+        raise TypeError("not expecting type '%s'" % type(s))
+    if six.PY2 and isinstance(s, text_type):
+        s = s.encode(encoding, errors)
+    elif six.PY3 and isinstance(s, binary_type):
+        s = s.decode(encoding, errors)
+    return s
+
+
 def binary_to_object_id(binary_object_id):
     return ray.ObjectID(binary_object_id)