attack prediction wrong for some weaponspecials with filters

[gfgtdf]

If a unit has an attack like tihs

[attack]
	damage=10
	number=2
	range="melee"
	type="impact"
	[specials]
		[damage]
			add=4
			[filter_self]
				formula = "hitpoints > 50"
			[/filter_self]
		[/damage]
	[/specials]
[/attack]

(lets assume tha unti has current 51 hp) the damage prediction code will assume that every attack does 14 damagebut during the actual fight all strikes that were made after the unit has <50 hp left do just 10 damage. Tested on wesnoth 1.13.8 release.

[CelticMinstrel]

Hmm, this seems kind of tricky. The obvious fix would be to save the unit's current hit points but then set it to various projected values as the attack prediction progresses, but I feel like there has to be a better way than that...

[CelticMinstrel]

(Also adding the Lua label because I assume this would also affect filters using lua_function.)