Polymorph - IndexError: list assignment index out of range

[Ragowit]

Deck 1: Arcane Intellect, Arcane Missiles, Bluegill Warrior, Murloc Tidehunter, Elven Archer, Elven Archer, Mirror Image, Arcane Missiles, Mirror Image, Bluegill Warrior, Arcane Explosion, Arcane Explosion, Frostbolt, Polymorph, Frostbolt, Kobold Geomancer, Arcane Intellect, Sen'jin Shieldmasta, Ogre Magi, Deathlord, Stonetusk Boar, Argent Squire, Haunted Creeper, Frost Elemental, Stormwind Champion, Ironfur Grizzly, Kobold Geomancer, Gelbin Mekkatorque, Silverback Patriarch, Sorcerer's Apprentice

Deck 2: Starfire, Kobold Geomancer, Blingtron 3000, Windfury Harpy, Blood Knight, Spectral Knight, Claw, Baron Rivendare, Stranglethorn Tiger, Razorfen Hunter, Mark of Nature, Echoing Ooze, Ironbeak Owl, Frostwolf Warlord, Frostwolf Warlord, Dark Iron Dwarf, Dark Iron Dwarf, Mind Control Tech, Piloted Shredder, Archmage, Spectral Knight, Loatheb, Mind Control Tech, Deathlord, Ancient of War, Magma Rager, Elite Tauren Chieftain, Stormwind Champion, Young Priestess, Ancient Brewmaster

Traceback (most recent call last):
  File "C:\Users\Ragowit\Documents\GitHub\mcts\hearthbreaker\uct.py", line 165, in DoMove
    self.game.play_card(self.game.current_player.hand[move[3]])
  File "C:\Users\Ragowit\Documents\GitHub\mcts\hearthbreaker\hearthbreaker\game_objects.py", line 2009, in play_card
    card.use(self.current_player, self)
  File "C:\Users\Ragowit\Documents\GitHub\mcts\hearthbreaker\hearthbreaker\cards\spells\mage.py", line 280, in use
    self.target.replace(minion)
  File "C:\Users\Ragowit\Documents\GitHub\mcts\hearthbreaker\hearthbreaker\game_objects.py", line 1165, in replace
    self.player.minions[self.index] = new_minion
IndexError: list assignment index out of range

[danielyule]

I'm able to replicate this one, but I don't know the cause. I could treat the symptom (i.e. stop the bug from happening), but I'd rather figure out why, since it should never be occurring. I will spend some time working on it.

[danielyule]

I ran these decks over and over again, recording which cards were being played, until I realized that Deathlord was the common factor. The bug was caused by Deathlord summoning its minion to the same index as it was currently sitting at, but on the other side.