But this raises in my mind the question of tracking CVS closely. How often have mysterious problems like this happened? Theoretically CVS should make it possible to roll backwards and forwards to different versions to get around problems like this (as well as to make it easy or at least possible to merge the canonical fixes by those with commit powers with one's own custom modifications).
But in reality, how well does this work? I've seen posts elsewhere about the hassles of reconciling one's own code with the moving target of the cvs code base. How do people make this work?