CLI `--webpack` flag doesn't appear to work

[swashcap]

Passing the --webpack config to kit-cli doesn't seem to work. My sample webpack.config.js:

throw new Error('hello?')

…doesn't bubble up to the CLI. Actually passing a config object doesn't seem to work, either (noticing specifically that stylus-loader isn't working.)

Versions:

$ node --version
v8.11.4
$ yarn list --pattern=@compositor/kit-cli
yarn list v1.12.1
└─ @compositor/[email protected]
   Done in 0.96s.

Any thoughts?