[2431] Remove obsolete comment

src/lib/dns/master_loader.cc

@@ -185,8 +185,6 @@ private:
         }
 
         if (*rrclass != zone_class_) {
-            // It doesn't really matter much what type of exception
-            // we throw, we catch it just below.
             isc_throw(InternalException, "Class mismatch: " << *rrclass <<
                       "vs. " << zone_class_);
         }