Fix 're' to work on bytes. It could do with a few more tests, though.
diff --git a/Lib/sre_compile.py b/Lib/sre_compile.py
index f3b415d..4f62416 100644
--- a/Lib/sre_compile.py
+++ b/Lib/sre_compile.py
@@ -472,7 +472,7 @@
     code[skip] = len(code) - skip
 
 def isstring(obj):
-    return isinstance(obj, str)
+    return isinstance(obj, (str, bytes))
 
 def _code(p, flags):