Comment explaining previous commit

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@4101 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/datasrc/memory_datasrc.cc

@@ -175,6 +175,9 @@ struct MemoryZone::MemoryZoneImpl {
         // This case should not happen because we enable callback only
         // when we add an RR searched for above.
         assert(0);
+        // This is here to avoid warning (therefore compilation error)
+        // in case assert is turned off. Otherwise we could get "Control
+        // reached end of non-void function".
         return (false);
     }