One aspect of source code management is how to deal with the almost inevitable need to upgrade your Caché or Ensemble platform to a newer InterSystems release.
It's long been my experience that InterSystems does a very good job of maintaining backward compatibility. Code that works correctly on, say, 2012.1 is very likely to work correctly on, say, 2015.2 without any modification.
I'd guess that few sites are in a position to take a "big bang" approach and upgrade all of their instances (e.g. dev, test, live, DR) at the same time. So how do we deal with having different instances running differe

