Question: What is a common-lisp analogue of python's argparse library for parsing command-line arguments?

Answer: 
There are a few including:

command-line-arguments -- <http://cliki.net/command-line-arguments>

getopt -- <https://github.com/keithj/getopt>

unix-options -- <https://github.com/astine/unix-options>

I haven't actually tried any of them but hopefully one of them fits your needs.
I have used `apply-argv` for our bundle-generator.