“There is only one code stream. You can develop in a temporary branch, but never let it live longer than a few hours. Multiple code streams are an enormous source of waste in software development. I fix a defect in the currently deployed software. Then I have to retrofit the fix to all the other deployed versions and the active development branch. Then you find that my fix broke something you were working on and you interrupt me to fix my fix. And on and on. There are legitimate reasons for having multiple versions of the source code active at one time. Sometimes, though, all that is at work is simple expedience, a micro-optimization taken without a view to the macro-consequences. If you have multiple code bases, put a plan in place for reducing them gradually. You can improve the build system to create several products from a single code base. You can move the variation into configuration files. Whatever you have to do, improve your process until you no longer need multiple versions of the code.”