safer string comparison

git-svn-id: https://svn.plone.org/svn/collective/bda.ldap/trunk@121989 db7f04ef-aaf3-0310-a811-c281ed44c4ad

Author: chaoflow

src/bda/ldap/users.py

@@ -96,7 +96,7 @@ def authenticate(self, id=None, login=None, pw=None):
         if pw is None:
             raise ValueError(u"You need to specify a password")
         if login:
-            if self._login_attr is self._key_attr:
+            if self._login_attr == self._key_attr:
                 id = login
             else:
                 id = self.idbylogin(login)