Added a check for file existance to prevent tag scanning.
Added a check for file existance to prevent tag scanning.

It is a workaround for bug T18572. At least it helps in
writing operations if the file does not exist.

MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK