PVS-Studio warning V523 for VTK

void vtkOBJExporter::WriteAnActor(....)
{
  ...
  if (i%2)
  {
    i1 = i - 1;
    i2 = i - 2;
  }
  else
  {
    i1 = i - 1;
    i2 = i - 2;
  }
  ...
}

This suspicious code was found in VTK project by PVS-Studio static code analyzer.
Warning message is:
V523 The 'then' statement is equivalent to the 'else' statement. vtkRendering vtkobjexporter.cxx 324

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/