Do not rewrite (ref: OpenMage/magento-lts#1513)

Author: justinbeaty

app/code/local/Cm/RedisSession/etc/config.xml

@@ -38,11 +38,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   </modules>
   <global>
     <models>
-      <core_resource>
-        <rewrite>
-          <session>Cm_RedisSession_Model_Session</session>
-        </rewrite>
-      </core_resource>
+      <cm_redissession>
+        <class>Cm_RedisSession_Model</class>
+      </cm_redissession>
     </models>
   </global>
 </config>