Restore extra backport changes

PowhegHooksVincia removed because of potential error with PR cms-sw#42020, however this commit exactly copies the file from the 13_1 backport. Hopefully this remedies the issue

GeneratorInterface/Pythia8Interface/plugins/Pythia8Hadronizer.cc

@@ -30,6 +30,7 @@ using namespace Pythia8;
 // Emission Veto Hooks
 //
 #include "Pythia8Plugins/PowhegHooks.h"
+#include "Pythia8Plugins/PowhegHooksVincia.h"
 #include "GeneratorInterface/Pythia8Interface/plugins/EmissionVetoHook1.h"
 
 // Resonance scale hook
@@ -133,6 +134,7 @@ class Pythia8Hadronizer : public Py8InterfaceBase {
   // Emission Veto Hooks
   //
   std::shared_ptr<PowhegHooks> fEmissionVetoHook;
+  std::shared_ptr<PowhegHooksVincia> fEmissionVetoHookVincia;
   std::shared_ptr<EmissionVetoHook1> fEmissionVetoHook1;
 
   // Resonance scale hook
@@ -388,7 +390,10 @@ bool Pythia8Hadronizer::initializeForInternalPartons() {
     (fUserHooksVector->hooks).push_back(fEmissionVetoHook1);
   }
 
-  if (fMasterGen->settings.mode("POWHEG:veto") > 0 || fMasterGen->settings.mode("POWHEG:MPIveto") > 0) {
+  bool VinciaShower = fMasterGen->settings.mode("PartonShowers:Model") == 2;
+
+  if ((fMasterGen->settings.mode("POWHEG:veto") > 0 || fMasterGen->settings.mode("POWHEG:MPIveto") > 0) &&
+      !VinciaShower) {
     if (fJetMatchingHook.get() || fEmissionVetoHook1.get())
       throw edm::Exception(edm::errors::Configuration, "Pythia8Interface")
           << " Attempt to turn on PowhegHooks by pythia8 settings but there are incompatible hooks on \n Incompatible "
@@ -401,6 +406,13 @@ bool Pythia8Hadronizer::initializeForInternalPartons() {
     (fUserHooksVector->hooks).push_back(fEmissionVetoHook);
   }
 
+  if (fMasterGen->settings.mode("POWHEG:veto") > 0 && VinciaShower) {
+    edm::LogInfo("Pythia8Interface") << "Turning on Vincia Emission Veto Hook from pythia8 code";
+    if (!fEmissionVetoHookVincia.get())
+      fEmissionVetoHookVincia.reset(new PowhegHooksVincia());
+    (fUserHooksVector->hooks).push_back(fEmissionVetoHookVincia);
+  }
+
   bool PowhegRes = fMasterGen->settings.flag("POWHEGres:calcScales");
   if (PowhegRes) {
     edm::LogInfo("Pythia8Interface") << "Turning on resonance scale setting from CMSSW Pythia8Interface";
@@ -555,7 +567,10 @@ bool Pythia8Hadronizer::initializeForExternalPartons() {
     }
   }
 
-  if (fMasterGen->settings.mode("POWHEG:veto") > 0 || fMasterGen->settings.mode("POWHEG:MPIveto") > 0) {
+  bool VinciaShower = fMasterGen->settings.mode("PartonShowers:Model") == 2;
+
+  if ((fMasterGen->settings.mode("POWHEG:veto") > 0 || fMasterGen->settings.mode("POWHEG:MPIveto") > 0) &&
+      !VinciaShower) {
     if (fJetMatchingHook.get() || fEmissionVetoHook1.get())
       throw edm::Exception(edm::errors::Configuration, "Pythia8Interface")
           << " Attempt to turn on PowhegHooks by pythia8 settings but there are incompatible hooks on \n Incompatible "
@@ -568,6 +583,13 @@ bool Pythia8Hadronizer::initializeForExternalPartons() {
     (fUserHooksVector->hooks).push_back(fEmissionVetoHook);
   }
 
+  if (fMasterGen->settings.mode("POWHEG:veto") > 0 && VinciaShower) {
+    edm::LogInfo("Pythia8Interface") << "Turning on Vincia Emission Veto Hook from pythia8 code";
+    if (!fEmissionVetoHookVincia.get())
+      fEmissionVetoHookVincia.reset(new PowhegHooksVincia());
+    (fUserHooksVector->hooks).push_back(fEmissionVetoHookVincia);
+  }
+
   bool PowhegRes = fMasterGen->settings.flag("POWHEGres:calcScales");
   if (PowhegRes) {
     edm::LogInfo("Pythia8Interface") << "Turning on resonance scale setting from CMSSW Pythia8Interface";
@@ -591,7 +613,6 @@ bool Pythia8Hadronizer::initializeForExternalPartons() {
       fTopRecoilHook.reset(new TopRecoilHook());
     (fUserHooksVector->hooks).push_back(fTopRecoilHook);
   }
-
   //adapted from main89.cc in pythia8 examples
   bool internalMatching = fMasterGen->settings.flag("JetMatching:merge");
   bool internalMerging = !(fMasterGen->settings.word("Merging:Process") == "void");