message: Update fem/bilinearform to use InitTVectors with Pi
diff: @@ -1641,9 +1641,10 @@ void MixedBilinearForm::FormRectangularLinearSystem(const Array<int>
  return;
  }
  + const Operator *Pi = this->GetProlongation();
  const Operator *Po = this->GetOutputProlongation();
  const Operator *Ri = this->GetRestriction();
  - InitTVectors(Po, Ri, x, b, X, B);
  + InitTVectors(Po, Ri, Pi, x, b, X, B);
  if (!mat_e)
  {
  