diff -r 2f123f309f61 -r 6f62a1c3e11d mercurial/byterange.py
--- a/mercurial/byterange.py	Fri Dec 29 05:27:00 2017 +0530
+++ b/mercurial/byterange.py	Fri Dec 29 05:28:05 2017 +0530
@@ -416,7 +416,7 @@
     if range_header is None:
         return None
     if _rangere is None:
-        _rangere = re.compile(r'^bytes=(\d{1,})-(\d*)')
+        _rangere = re.compile(br'^bytes=(\d{1,})-(\d*)')
     match = _rangere.match(range_header)
     if match:
         tup = range_tuple_normalize(match.group(1, 2))