When we were getting very close to releasing Half-Life 1 (less than a week or so), we found there were already some projects that we needed to start working on, but we couldn't risk checking in code to the shipping version of the game. At that point we forked off the code in VSS to be both $/Goldsrc and
Never underestimate the bandwidth of a station wagon full of tapes. -- Dr. Warren Jackson, Director, UTCS