I do that too, with a function in my .profile that I can call in the `dotfiles/local` [1]. That lets me "advise" the global version of the file with before:

    cat ~/dotfiles/local/profile
    SETUP=goes.here
    load-global-config "$BASH_SOURCE"

after:

    cat ~/dotfiles/local/profile
    load-global-config "$BASH_SOURCE"
    MODIFY=${EXISTING:settings}
    OVERWRITE=options
    OTHER=things.too

and "around":

    cat ~/dotfiles/local/profile
    echo "BEFORE"
    load-global-config "$BASH_SOURCE"
    echo "AND AFTER"

The nice thing about keeping local dotfiles in a separate directory is that you can `.gitignore` it for your "public" dotfiles repository, but still keep the local dotfiles under source control easily.

[1]: https://github.com/svieira/dotfiles/blob/4b7e948b698b623a498...