EDIT: To be clear - maybe I am REALLY old-school, but every time we did a release, we archived our tool-chain (GCC blah blah, Make blah blah, bash blah blah), our depencies, our vendor libraries and our code, so that IF in 20 years, if we had to rebuild a particular release (12.x) for a particular client (Chase) on a particular platform (AIX), we could do so de novo. Maybe that was overkill, but in a world where everything changes, why wouldn't you snapshot everything for every release?