message: The row_starts of Rt are not touched, it's the col_starts we need to check.
diff: @@ -1509,7 +1509,7 @@ HypreParMatrix * RAP(HypreParMatrix * Rt, HypreParMatrix *A, HypreParMatrix *P)
  }
  if (Rt_owns_its_col_starts)
  {
  - hypre_ParCSRMatrixSetRowStartsOwner(*Rt, 1);
  + hypre_ParCSRMatrixSetColStartsOwner(*Rt, 1);
  }
  return new HypreParMatrix(rap);
  