By quick observation, I found this problem goes away if following change
is applied.

Index: Lib/_strptime.py
===================================================================
--- Lib/_strptime.py	(revision 69496)
+++ Lib/_strptime.py	(working copy)
@@ -262,7 +262,7 @@
 
     def compile(self, format):
         """Return a compiled re object for the format string."""
-        return re_compile(self.pattern(format), IGNORECASE | ASCII)
+        return re_compile(self.pattern(format), IGNORECASE)
 
 _cache_lock = _thread_allocate_lock()
 # DO NOT modify _TimeRE_cache or _regex_cache without acquiring the
cache lock

But this is just an observation. I don't call this *fix* because I'm not
familier with unicode, this change might cause another problem if applied.