This morning I have been reviewing some code that has been checked into TFS based on work items I have created. When reviewing files that have been checked into source control, several times I have seen code commented out (old version of the code), with code added below the commented block (new version of the code).

I never quite understood this particular behaviour. What is the point of leaving commented old/dead code in source control. Isn’t that what source control and commented version entries are for?