Move the validate_header_name up

Author: srinivasreddy

Lib/email/policy.py

@@ -144,9 +144,9 @@ def header_store_parse(self, name, value):
         CR or LF characters.
 
         """
+        validate_header_name(name)
         if hasattr(value, 'name') and value.name.lower() == name.lower():
             return (name, value)
-        validate_header_name(name)
         if isinstance(value, str) and len(value.splitlines())>1:
             # XXX this error message isn't quite right when we use splitlines
             # (see issue 22233), but I'm not sure what should happen here.