Change exc.desc to exc, desc was not always present

Author: Daniel Mollberg

nipap/nipap/authlib.py

@@ -360,7 +360,7 @@ def authenticate(self):
                         self.readonly = True
 
         except (ldap.NO_SUCH_OBJECT,ldap.OPERATIONS_ERROR,ldap.FILTER_ERROR,ldap.INVALID_DN_SYNTAX,ldap.SERVER_DOWN) as exc:
-            raise AuthError(exc.desc)
+            raise AuthError(exc)
         except KeyError:
             raise AuthError('LDAP attribute missing')
         except IndexError: