- add notes that @comparator and @expression don't go together.

Change-Id: I3fb366f8b49454453e4b6dada565c24c5ccb975e
(cherry picked from commit 8965f30215)

lib/sqlalchemy/ext/hybrid.py

@@ -328,6 +328,10 @@ behavior of each SQLAlchemy expression operator individually.  They
 are useful when creating custom types that have some highly
 idiosyncratic behavior on the SQL side.
 
+.. note::  The :meth:`.hybrid_property.comparator` decorator introduced
+   in this section **replaces** the use of the
+   :meth:`.hybrid_property.expression` decorator.  They cannot be used together.
+
 The example class below allows case-insensitive comparisons on the attribute
 named ``word_insensitive``::
 
@@ -784,6 +788,10 @@ class hybrid_property(interfaces.InspectionAttrInfo):
         The return value of the decorated method should be an instance of
         :class:`~.hybrid.Comparator`.
 
+        .. note::  The :meth:`.hybrid_property.comparator` decorator
+           **replaces** the use of the :meth:`.hybrid_property.expression`
+           decorator.  They cannot be used together.
+
         """
 
         proxy_attr = attributes.\