message: Protection against assigning chi2<0
  With ill-formed covariance matrix once in a while negative chi2 is assigned, leading to FPE afterwards
diff: @@ -94,7 +94,7 @@ public:
  Bool_t GetGoldV0() const {return fGoldV0;}
  void SetGoldV0(Bool_t g) {fGoldV0=g;}
  Float_t GetChi22() const {return fChi22;}
  - void SetChi22(Float_t c) {fChi22=c;}
  + void SetChi22(Float_t c) {fChi22 = c<0.f ? 999.f : c;}
  Float_t GetDeadZoneProbability(Int_t ilayer) const {return fDeadZoneProbability[ilayer];}
  void SetDeadZoneProbability(Int_t ilayer,Float_t d) {fDeadZoneProbability[ilayer]=d;}
  //
  