Is it possible to sacrifice guard droids?

[jynki]

I have heard people saying that they use guard droids + repair droids + sacrifice to sacrifice guard droids and then heal them with repair droids to avoid having to buy troops. however in my version 1.2 the guard droids cannot be sacrificed (just a question mark when I try to sacrifice them, all other units work to sacrifice). I was wondering if anyone know if there is a certain patch where it works to sacrifice guard droids since some people seem to be able to get it to work?