In Split(), fix removal from a set being iterated, leading to exception at study restoration if there are intersecting groups
In Split(), fix removal from a set being iterated, leading to exception at study restoration if there are intersecting groups

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