This still relies on bash_completion, right? What's the output going to be for people who don't have this?

My reading of @sorbits's suggestion was that you'd do something like `if [[ $(type -t _get_comp_words_by_ref) == "function" ]]` to check for bash_completion, and then assume that bash_completion exists in that branch and do the -f and -C in that branch. Then people who have bash_completion get completion for -f and -C automatically, and others are unperturbed. Does that sound reasonable?