Dictionary .get corrupts variable on failure

[asumagic]

Not 100% sure as I didn't diagnose in too deep but it seemed to be what caused #167.

See:

s32 ReadCost(ConfigFile cfg, dictionary@ costs, const string &in cost_name, s32 &in cost)
{
	if (!costs.get(cost_name, cost) && cfg.exists(cost_name))
	{
		cost = cfg.read_s32(cost_name, cost);
		costs.set(cost_name, cost);
	}

	return cost;
}

Changing the type of cost to s32 (instead of s32 &in) did not help.

[asumagic]

repro: int test = 123; dictionary foo; foo.get("foo", test); print(''+test)
80