--target-browsers is being ignored in the context of postcss

When running with:

--target-browsers \"Firefox >=44,Chrome >=48,IE >=9,last 2 version\"

it should pass this to autoprefixer in the postcss stage

export default function configure(pkg, opts) {
  const cc = postcss([cssimport, cssnext])
      , map = opts.debug? { inline: false } : false

this does not take into account opts.targetBrowsers

const cc = postcss([cssimport, cssnext({browsers: opts.targetBrowsers}])

Currently, used in js here:

zambezi / ez-build