In case a completion needs a function from another script, run
`complete -C"foo "` to load it, so the full autoloading logic is used.
Otherwise these things break if the path is off. E.g. cargo's version
will fail if you override the cargo completion in
~/.config/fish/completions without also overriding the rustup
completions.
In other cases, fix for empty $__fish_data_dir, which will be coming in the next commit
