Rename io.open import to limite side-effects

synapse/config/_base.py

@@ -16,7 +16,7 @@
 import argparse
 import errno
 import os
-from io import open
+from io import open as io_open
 from textwrap import dedent
 
 from six import integer_types
@@ -132,7 +132,7 @@ class Config(object):
     @classmethod
     def read_file(cls, file_path, config_name):
         cls.check_file(file_path, config_name)
-        with open(file_path, encoding="utf-8") as file_stream:
+        with io_open(file_path, encoding="utf-8") as file_stream:
             return file_stream.read()
 
     @staticmethod