Huh I had no idea $1/$2/etc worked as-is in an alias. The advice I learned years ago for dealing with any alias that needs to do something custom with parameters is to write it like

  git config alias.foo '!f() { actual command goes here }; f'

as that will pass all the args to the shell function. But if git is already setting it up so the args work then suffixing the alias with ";:" seems simpler.

Interesting! Thanks for digging up the code.