revert to using codecs.open() for output files instead of io.open() as the...

revert to using codecs.open() for output files instead of io.open() as the latter cannot write str objects in text mode under Py2 (and we erroneously do that in some spots)

Cython/Utils.py

@@ -7,6 +7,7 @@ import os
 import sys
 import re
 import io
+import codecs
 
 modification_time = os.path.getmtime
 
@@ -49,7 +50,9 @@ def open_new_file(path):
     # ASCII strings or (e.g. for file names) byte encoded strings as
     # Unicode, so we need a direct mapping from the first 256 Unicode
     # characters to a byte sequence, which ISO-8859-1 provides
-    return io.open(path, "w", encoding="ISO-8859-1")
+
+    # note: can't use io.open() in Py2 as we may be writing str objects
+    return codecs.open(path, "w", encoding="ISO-8859-1")
 
 
 def castrate_file(path, st):