As a follow up to the question ‘What does the output of TeX/LaTeX depend on (in the sense of version and distribution)’, I wonder if there are any tools (or at least plans to ship such a tool) which would allow noting a specific version of all packages being used and the tool would make sure that all TeX sources are being built with those packages (and their dependencies). Similar to how most of the modern [*] programming languages do it (eg. http://bundler.io).
tlmgr to upgrade all packages from CTAN (or installing a new TeXLive) feels like a very stupid thing to do when something changes in a package and messes with one’s documents. (And one might not even notice immediately.)
[*] Not sure if modern is the right word here, as there is even a package management tool for vim now: Vundle.