diff -r e159cb0d955b Lib/urllib/robotparser.py
--- a/Lib/urllib/robotparser.py	Sun Apr 27 10:44:46 2014 -0700
+++ b/Lib/urllib/robotparser.py	Mon Apr 28 13:44:51 2014 +0100
@@ -62,6 +62,7 @@
         else:
             raw = f.read()
             self.parse(raw.decode("utf-8").splitlines())
+            self.modified()
 
     def _add_entry(self, entry):
         if "*" in entry.useragents: