[vezzy-fnord]

Rebar does not even guarantee repeatable builds

I think you're setting the bar a little high there. Reproducible builds is something that most package managers, OS and language-specific alike, struggle with to this day. Only Nix and Guix have complete solutions, I think.

[pawelkowal]

Certainly Rubygems+Bundler in Ruby does it, as well as Mix in Elixir. npm in node.js may even do it due to its weird require system but I am not sure.