BUG: Fixing psib to use products mixture.

Fix Gitlab issue #1423

src/thermophysicalModels/reactionThermo/psiuReactionThermo/heheuPsiThermo.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
                             | Copyright (C) 2011-2016 OpenFOAM Foundation
@@ -611,7 +611,7 @@ Foam::heheuPsiThermo<BasicPsiThermo, MixtureType>::psib() const
     forAll(psibCells, celli)
     {
         psibCells[celli] =
-            this->cellReactants(celli).psi(pCells[celli], TbCells[celli]);
+            this->cellProducts(celli).psi(pCells[celli], TbCells[celli]);
     }
 
     volScalarField::Boundary& psibBf = psib.boundaryFieldRef();