Prevent error message when deep copying vtkGridTransform

Change-Id: I99c13233c9870f25b34947e071a9a23e33d710c2
Change GetInputConnection error message into a debug warning message

Change-Id: Ide8b69796a73b910d877a9c716de9e93f63fa29b
Merge topic 'getinputconnection-error-message' into master

1d7b0a7b Change GetInputConnection error message into a debug warning message
c62a84d8 Prevent error message when deep copying vtkGridTransform