The first thread about it on IC2 forums is dated 2012. It's still not fixed, BC devs telling that it's IC2's fault and vice versa:
Bug: Buildcraft gates use upgrade slots when processing inventory conditions
https://github.com/BuildCraft/BuildCraft/issues/4442
Can someone who understands what are the "triggers" and "hooks" these people are talking about tell me whose fault it is actually?