Ionic 2 beta 11 Firefox http json bug (?)

I’m using django rest framework which sensetive to “accept” header.
My app doesn’t work in latest firefox.
The reason because of http request:

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

it not specifying “JSON”

example header for ionic 1 in the same firefox

Accept: application/json, text/plain, */*

my code snippet:

import { Http } from '@angular/http';
  constructor(private http: Http, .....) {

should I create an issue or this is expected behavior?