On one hand, exactly, anything that's grabbed from the distro is actually an issue to reproducibility, but I guess it also means there could be some shim to make installing things easier (assuming `apt/pacman/whatever install blaze` isn't enough to get going, which I guess may be the case since bootstrapping toolchains might not be straightforward and needs configuration/smashing-your-head-against-the-wall for each language, especially if it's not already supported like C++/Java).