Preparation for Pythia8315 (#14286)

Preparations for Pythia8315

* Ignore nuclei isospin only if equal to 9.
* Do not change the PDG code of beam remnants

Author: pzhristov

Generators/src/GeneratorPythia8.cxx

@@ -657,7 +657,7 @@ Bool_t
     auto st = o2::mcgenstatus::MCGenStatusEncoding(particle.statusHepMC(), //
                                                    particle.status())      //
                 .fullEncoding;
-    mParticles.push_back(TParticle(particle.id(),            // Particle type
+    mParticles.push_back(TParticle(pdg,                      // Particle type
                                    st,                       // status
                                    particle.mother1() - 1,   // first mother
                                    particle.mother2() - 1,   // second mother
@@ -776,7 +776,11 @@ void GeneratorPythia8::updateHeader(o2::dataformats::MCEventHeader* eventHeader)
                               hiinfo->nAbsProj() + hiinfo->nDiffProj());
     eventHeader->putInfo<int>(Key::nPartTarget,
                               hiinfo->nAbsTarg() + hiinfo->nDiffTarg());
+#if PYTHIA_VERSION_INTEGER >= 8313
+    eventHeader->putInfo<int>(Key::nCollHard, hiinfo->nCollND());
+#else
     eventHeader->putInfo<int>(Key::nCollHard, hiinfo->nCollNDTot());
+#endif
   }
 }