How to supress/fix Susy 2.0 deprecated warnings

I am trying to suppress/fix a deprecated warning from my grunt-sass (based on node-sass) compile that I traced to Susy 2 using functions listed to deprecate in Sass 4.0. At this point, it's not feasible to upgrade to Susy 3 as there's no upgrade guide and will break a large website.

Node-sass offers a --quiet option that I've passed in my Gruntfile.js though I am still getting the warning. This is my SASS section in my Gruntfile.js.

sass: {
    options: {
        quiet: true,
        sourceMap: false,
        outputStyle: 'compressed'
    },
    dist: {
        options: {
            quiet: true 
        },
       files: {
           'static/css/style.min.css' : 'static/css/sass/style.scss',
           'static/css/orderform.css' : 'static/css/sass/orderform.scss'
       }
    }
}

Is there a way to suppress deprecated warnings? Just ignoring the warnings will slow down my development, outputting all the warnings increases my compile time from ~1s to ~4s.

Here is the log output

Version 2.2.14 was specifically released to solve this problem. I tried to reproduce this locally in 2.2.14, but I'm not able to. I do get the warning when I write an improper call() - but I'm not able to get the same warning from Susy. Are you sure the version of Susy being used is the version in npm?