fixed bug in _doAddUser() where encrypted password become encrypted another time

lib/python/AccessControl/User.py

@@ -1044,7 +1044,8 @@ class UserFolder(BasicUserFolder):
 
     def _doAddUser(self, name, password, roles, domains, **kw):
         """Create a new user"""
-        if password is not None and self.encrypt_passwords:
+        if password is not None and self.encrypt_passwords \
+                                and not self._isPasswordEncrypted(password):
             password = self._encryptPassword(password)
         self.data[name]=User(name,password,roles,domains)