*Fix crash.

--HG--
branch : trunk

src/game/SpellAuras.cpp

@@ -1010,6 +1010,11 @@ void Aura::SetStackAmount(uint8 stackAmount)
     RefreshAura();
 }
 
+void Aura::InitStackAmount(uint8 stackAmount)
+{
+    m_stackAmount = stackAmount;
+}
+
 bool Aura::modStackAmount(int32 num)
 {
     // Can`t mod

src/game/SpellAuras.h

@@ -279,6 +279,7 @@ class TRINITY_DLL_SPEC Aura
         //int32 GetModifierValuePerStack() {return m_modifier.m_amount / m_stackAmount;}
         void SetStackAmount(uint8 num);
         bool modStackAmount(int32 num); // return true if last charge dropped
+        void InitStackAmount(uint8 stackAmount);
         uint32 GetAuraStateMask(){return m_auraStateMask;}
         void SetAuraState(uint8 num){m_auraStateMask |= 1<<(num-1);}  //modifies aura's aura state (not unit!)
         void RefreshAura();

src/game/Unit.cpp

@@ -3795,9 +3795,9 @@ bool Unit::AddAura(Aura *Aur)
                     {
                         // prevent adding stack more than once
                         stackModified=true;
-                        Aur->SetStackAmount(i2->second->GetStackAmount());
+                        Aur->InitStackAmount(i2->second->GetStackAmount());
                         if(Aur->GetStackAmount() < aurSpellInfo->StackAmount)
-                            Aur->SetStackAmount(Aur->GetStackAmount()+1);
+                            Aur->InitStackAmount(Aur->GetStackAmount()+1);
                     }
                     RemoveAura(i2,AURA_REMOVE_BY_STACK);
                     i2=m_Auras.lower_bound(spair);