Bug: preview works correctly only once, other times preview shows the same as at the 1st time.
Bug: preview works correctly only once, other times preview shows the same
as at the 1st time.

Ensure clearing of tmp mesh

FedoraScientific/salome-smesh,FedoraScientific/salome-smesh,FedoraScientific/salome-smesh,FedoraScientific/salome-smesh