[jacquesm]

I have no problem running stuff from a decade ago either on the same box and installation that it was on a decade ago. But virtual environments and pip freeze are closer to mothballing an old box than displaying long term code compatibility and functionality. Their main reason to exist is as a workaround precisely because there are such issues.

The whole idea that you need a multitude of environments to support applications written in the same interpreted language is where it breaks, that should not have been necessary if backwards compatibility had not been an issue.