Crash on response 'Link" header parsing

[ivailop]

Since yesterday, the "Link" header returned when doing Web application flow, i.e.

POST  login/oauth/access_token

is formatted in a way that results in a crash when calling exchange_code_for_token:

NoMethodError: undefined method `captures' for nil:NilClass
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:52:in `block in process_rels'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:51:in `map'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:51:in `process_rels'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:20:in `initialize'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/agent.rb:107:in `new'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/agent.rb:107:in `call'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/connection.rb:156:in `request'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/connection.rb:28:in `post'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/client/users.rb:57:in `exchange_code_for_token'

Besides questioning why GitHub API changed, apparently sawyer has a bug!

FYI, to address the bug, in sawyer, I opened lostisland/sawyer#68 issue and related lostisland/sawyer#69 PR.

[osowskit]

@swinton any insight into recent changes that may have broken this?

[jeremie-stripe]

If it helps anyone, we are working around this by introducing a Faraday middleware step to strip the Link header in this situation (since the JS libraries are irrelevant in this case):

class LinkHeaderRemover < Faraday::Response::Middleware
  OAUTH_LOGIN_URL_PATH = "/login/oauth/access_token"

  def on_complete(env)
    request_path = URI(env.url).path
    return if request_path != OAUTH_LOGIN_URL_PATH

    response_headers = env.response_headers
    return if response_headers.nil?

    response_headers.delete("link")
  end
end

Setup in your pipeline like so:

middleware = Octokit::Default.middleware.dup
middleware.insert_before(middleware.handlers.length - 1, LinkHeaderRemover)
Octokit.middleware = middleware

[tarebyte]

I think this has been fixed on the GitHub side, is anyone running into these issues still?