HttpOnly cookie handling

[adam-eltanbouli]

I am not sure if this is an issue or my inexperience with Brython...

Scenario:
Request A receives HttpOnly cookie from backend (containing some token). Request B afterwards needs this cookie to authenticate.

Symptoms:

1. request A gets the cookie (visible in inspect -> Network -> request cookies and in request headers as 'set-cookie', but NOT VISIBLE in inspect -> Application -> Cookies)
2. request B sends no cookie despite flag 'withCredentials' being sent to true in both requests
3. Writing the very same code as plain JavaScript XHR (code is almost identical to Brython) and then using callback from Brython resolved the issue (when called from plain JavaScript XHR - cookie is handled properly in both request A and request B)