Start with a clean globalCellData_ for each data gathering.

Otherwise there might entries from the last call that should
either not be there this time or might have a different size.

opm/autodiff/ParallelDebugOutput.hpp

@@ -594,6 +594,7 @@ namespace Opm
 
                 const Wells* wells = wells_manager.c_wells();
                 globalWellState_.init(wells, *globalReservoirState_, globalWellState_ );
+                globalCellData_->clear();
             }
 
             PackUnPackSimulationDataContainer packUnpack( localReservoirState, *globalReservoirState_,