Getting an exception when following redirects

Making a GET request on a URI that follows redirects like so:

 payload = [
      body: "",
      follow_redirects: true,
      headers:
      [
        "...": ...,
        "Content-Type": "application/json",
      ]
    ]

HTTPotion.get "api.example.com/path/to/resource", payload

Produces an ArgumentException from the URI module:

** (ArgumentError) you must merge onto an absolute URI
    (elixir) lib/uri.ex:518: URI.merge/2
    (httpotion) lib/httpotion.ex:455: HTTPotion.normalize_location/2
    (httpotion) lib/httpotion.ex:455: HTTPotion.request/3
    (project) lib/file.ex:60: File.function/1

Specifically this exception occurs when I send an authenticated request to the Coinbase accounts endpoint.

I'm admittedly new to both Elixir and this library: but I suspect this error is being caused because the Coinbase API is returning an odd URI string which HTTPotion's normalize_location/2 function calls URI.merge/2 with the odd URI from the redirect, which is constructed without prepending http[s]:// to the URI. This causes the authority key in the URI struct to end up nil, meaning that URI.merge/2 is the specific version of the function being called. I'm trying to dig into the library a bit more to find out how to print the exact URI string that's being returned from the redirect.

This hasn't happened for the other Coinbase calls (this function for example), my suspicion is that when HTTPotion follows a redirect, the resulting string that URI is expected to parse is formed in a way that URI/HTTPotion doesn't expect.

If this isn't expected behavior, I'd like to submit a PR to prevent this exception from being thrown. Otherwise, guidance is appreciated.

valpackett / httpotion

Getting an exception when following redirects #131