1.6.0 ignores cli arguments

When command line arguments are provided, they no longer have any impact on the outcome.

Given file.less:

/*! hello */
/*! world */
foo { bar: 1 }

and compiled using:

lessc file.less --clean-css="--s1 --advanced --compatibility=ie8" file.css

Expected outcome:

/*! hello */foo{bar:1}

Actual outcome:

/*! hello *//*! world */foo{bar:1}

Context

package.json:

{
  "dependencies": {
    "less": "^4.2.0",
    "less-plugin-clean-css": "^1.6.0"
  }
}

clean-css: 5.3.3
less-plugin-clean-css: 1.6.0
less: 4.2.0

Reproduce the issue with the lessc command and the versions listed in package.json, then trace how the plugin receives and forwards the --clean-css arguments. Done means the supplied options affect compression so the output retains only one /*! comment, matching the expected CSS.