I think we could just launch the same job twice and check if the packages we got are the same (it supposed to be because is an automated process) after that we could see what's next
For one thing, at least the Qt client build captures the build date. The date would need to be set to something static, epoch 1 for example. But my opinion is that capturing the source revision that got used as input is more pertinent (what we already have as the RELEASE_VERSION variable in the packaging (ring-project repo) Makefile).