[0x0]

Sounds dangerous. Later commits on master might actually add more if(feature-flag) statements, so if you then just mindlessly merge the cleanup branch, you'll miss the added ifs.

I'd prefer to create a cleanup branch like any other feature branch only when actually going to clean up, and spend the extra cost getting back in context, studying all the if(feature-flags) from master. Otherwise you might miss some, or you might forget some interaction that you learned after feature deploy.

[pkaeding]

Yeah, I think if you mindlessly do anything, you're gonna have a bad time.

Think of the cleanup branch as a running list of changes that you know you will need to make to remove the flag. Any future references to the flag should keep this cleanup list in mind. Code reviewers should keep these cleanup lists in mind.

This list of cleanup tasks happens to be expressed as a branch in your VCS (this is a pretty good way to express changes that need to be applied to a codebase). You will still need to be careful when you execute that list, but it will be helpful to have the running tally of things that need to be done.