Fix validity check of cases in graph::helper.

src/graph/helper.cc

@@ -121,7 +121,7 @@ namespace hpp {
               static const bool valid =
                    ( (gCase & WithPreGrasp) || (gCase & GraspOnly) || (gCase & NoGrasp) )
                 && ( (gCase & WithPrePlace) || (gCase & PlaceOnly) || (gCase & NoPlace) )
-                && !(gCase == (NoGrasp | NoPlace));
+                && !((gCase & NoGrasp) && (gCase & NoPlace));
 
               static const std::size_t nbWaypoints = (pregrasp?1:0) + (intersec?1:0) + (preplace?1:0);
               static const std::size_t Nnodes = 2 + nbWaypoints;