raise a better error

git-svn-id: http://svn.python.org/projects/python/trunk@67348 6015fed2-1504-0410-9fe1-9d1591cc4771

Author: benjamin.peterson

Lib/optparse.py

@@ -799,7 +799,7 @@ def take_action(self, action, dest, opt, value, values, parser):
             parser.print_version()
             parser.exit()
         else:
-            raise RuntimeError, "unknown action %r" % self.action
+            raise ValueError("unknown action %r" % self.action)
 
         return 1