DB/Spells: correct more spelldifficulty_dbc entries

* add log message to find wrong entries

sql/updates/world/2014_01_04_02_world_spelldifficulty_dbc.sql

@@ -0,0 +1,6 @@
+DELETE FROM `spelldifficulty_dbc` WHERE `spellid0` IN (31956,36127,49380,59803,49381);
+INSERT INTO `spelldifficulty_dbc` (`id`, `spellid0`, `spellid1`, `spellid2`, `spellid3`) VALUES
+(31956,31956,38801,0,0),
+(36127,36127,39005,0,0),
+(49380,49380,59803,0,0),
+(49381,49381,59805,0,0);

src/server/game/DataStores/DBCStores.cpp

@@ -482,7 +482,8 @@ void LoadDBCStores(const std::string& dataPath)
             continue;
 
         for (int x = 0; x < MAX_DIFFICULTY; ++x)
-            sSpellMgr->SetSpellDifficultyId(uint32(newEntry.SpellID[x]), spellDiff->ID);
+            if (newEntry.SpellID[x])
+                sSpellMgr->SetSpellDifficultyId(uint32(newEntry.SpellID[x]), spellDiff->ID);
     }
 
     // create talent spells set

src/server/game/Spells/SpellMgr.cpp

@@ -455,6 +455,8 @@ uint32 SpellMgr::GetSpellDifficultyId(uint32 spellId) const
 
 void SpellMgr::SetSpellDifficultyId(uint32 spellId, uint32 id)
 {
+    if (uint32 i = GetSpellDifficultyId(spellId))
+        TC_LOG_ERROR("spells", "SpellMgr::SetSpellDifficultyId: Spell %u has already spellDifficultyId %u. Will override with spellDifficultyId %u.", spellId, i, id);
     mSpellDifficultySearcherMap[spellId] = id;
 }
 
@@ -480,7 +482,7 @@ uint32 SpellMgr::GetSpellIdForDifficulty(uint32 spellId, Unit const* caster) con
     SpellDifficultyEntry const* difficultyEntry = sSpellDifficultyStore.LookupEntry(difficultyId);
     if (!difficultyEntry)
     {
-        TC_LOG_DEBUG("spells", "SpellMgr::GetSpellIdForDifficulty: SpellDifficultyEntry not found for spell %u. This should never happen.", spellId);
+        TC_LOG_ERROR("spells", "SpellMgr::GetSpellIdForDifficulty: SpellDifficultyEntry not found for spell %u. This should never happen.", spellId);
         return spellId; //return source spell
     }