relates to:

• SR-3252 URLSession dataTask doesn't follow redirects

Issue Description:

HTTP headers are supposed to be case insensitive

In Open Source Foundation, if the HTTP server responds with a 302 and the location field has "location" (and not "Location"), the redirect won't be followed

Note that macOS Foundation solves this by normalizing the header fields dictionary:

let resp = HTTPURLResponse(url: URL(string: "http://localhost")!, statusCode: 300, httpVersion: nil, headerFields: ["location": "http://google.com"])!
print(resp.allHeaderFields)

On macOS this prints:

[AnyHashable("Location"): http://google.com]

On Linux this prints:

[AnyHashable("location"): "http://google.com"]