Bug: Post methods return an http error but the command works

[clementallen]

Steps to replicate:
Run the following:

const smithers = new Smithers('https://jenkinsurl.com', {
    crumbIssuer: true,
    auth: {
        username: '**username**',
        password: '**password**'
    }
});

smithers.startQuietDown().then(console.log).catch(console.warn);

Jenkins will start quiet mode correctly but the following error will be returned from Smithers:

Error: 403 | Forbidden
    at exports.default.error (/www/github/smithers/lib/utils/formatError.js:18:12)
    at /www/github/smithers/lib/Caller.js:49:49
    at Generator.throw (<anonymous>)
    at step (/www/github/smithers/lib/Caller.js:17:191)
    at /www/github/smithers/lib/Caller.js:17:402
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)