[.75] Exploit / Inconsistency in army build/upgrade

I noticed that the cost of increasing the size of an army is only paid with a *small* amount of Gildar and do not take in account the resources requirements (i.e. metal & crystal).

Therefore, easy thing to do is build a party of 3, and then upgrade to a company of 6 at a ridiculous cost (a few tenth of Gildar to replace many dozens of crystal & metal). I think this is an exploit due to a missing check rather than an inconsistency.