Www-Authenticate on iOS

I have a weird issue, one that actually took me a while to isolate, simply because of all places to look that was one of the last.

I connect to a server, and it replies with a 401 as it is supposed to, and in the WWW-Authenticate header field, it’ll tell me where to go to get authenticated.

It works fine on Andriod, but not on iOS.

It turns out that ion iOS, the name of the WWW-Authenticate header is changed to Www-Authenticate

I wonder if this problem is in the Safari browser, or the Angular2 Http module of iOS?