make and use equilGrid only on IO process.

With the change of CPgrid to only holding the grid on one process
it will be an empty grid on all other processes. This has really
strange side effects like Schedule::filterConnections removing all
well perforations on theses processes.

ebos/eclcpgridvanguard.hh

@@ -244,6 +244,7 @@ public:
         int mpiRank;
         MPI_Comm_rank(MPI_COMM_WORLD, &mpiRank);
         assert(mpiRank == 0);
+        assert(equilCartesianIndexMapper_);
 #endif
         return *equilCartesianIndexMapper_;
     }
@@ -280,8 +281,16 @@ protected:
         // the initial condition is calculated.
         // After loadbalance grid_ will contain a global and distribute view.
         // equilGrid_being a shallow copy only the global view.
-        equilGrid_ = new Dune::CpGrid(*grid_);
-        equilCartesianIndexMapper_ = new CartesianIndexMapper(*equilGrid_);
+        if (grid_->size(0))
+        {
+            equilGrid_ = new Dune::CpGrid(*grid_);
+            equilCartesianIndexMapper_ = new CartesianIndexMapper(*equilGrid_);
+        }
+        else
+        {
+            equilGrid_ = nullptr;
+            equilCartesianIndexMapper_ = nullptr;
+        }
 
         globalTrans_ = nullptr;
     }
@@ -289,11 +298,11 @@ protected:
     // removing some connection located in inactive grid cells
     void filterConnections_()
     {
-        assert(grid_);
-        Grid grid = *grid_;
-        grid.switchToGlobalView();
-        const auto eclipseGrid = Opm::UgGridHelpers::createEclipseGrid(grid, this->eclState().getInputGrid());
-        this->schedule().filterConnections(eclipseGrid);
+        if (equilGrid_)
+        {
+            const auto eclipseGrid = Opm::UgGridHelpers::createEclipseGrid(equilGrid(), this->eclState().getInputGrid());
+            this->schedule().filterConnections(eclipseGrid);
+        }
     }
 
     Grid* grid_;