In my case I have a `http_proxy` env variable on my development computer which passes all traffic to my vpn, however this proxy would fail to work when hostname is `localhost`, therefore when I'm testing my application it always fails because I setup my server at localhost, I want a method to force axios receiving a `none` for proxy config, currently if `proxy` property is `null` or `undefined` it will use the `http_proxy` env
lib/adapters/http.js
});
    
    req.on('error', function handleRequestError(err) {
      if (req.aborted) return;
      reject(enhanceError(err, config, null, req));
    });
    
    if (config.timeout && !timer) {
      timer = setTimeout(function handleRequestTimeout() {
        req.abort();
        reject(createError('timeout of ' + config.timeout + 'ms exceeded', config, 'ECONNABORTED', req));
      }, config.timeout);
    }
    if (config.cancelToken) {
      
      config.cancelToken.promise.then(function onCanceled(cancel) {
        if (req.aborted) return;
        req.abort();
        reject(cancel);
      });
    }
    
    if (utils.isStream(data)) {
      data.pipe(req);
    } else {
      req.end(data);
    }
  });
};