Fix reusing old OAuth tokens stored in Authorizations API

For people who are using hub for a longer time now, hub has stored an OAuth
token in Authorizations API with a `note_url` value that is now outdated
(e.g. "http://defunkt.io/hub/"). The newer `oauth_app_url` doesn't match
that, so the token is not reused. Hub tries to create a new OAuth token
with a `note` that says "hub" which fails with a 422 because it already
exists.

This fixes reusing old OAuth tokens even if the `note_url` doesn't match
anymore. Any key with `note` that says "hub" will get reused.

Fixes #496

features/authentication.feature

@@ -58,6 +58,36 @@ Feature: OAuth authentication
     And the exit status should be 0
     And the file "../home/.config/hub" should contain "oauth_token: OTOKEN"
 
+  Scenario: Re-use existing authorization with an old URL
+    Given the GitHub API server:
+      """
+      require 'rack/auth/basic'
+      get('/authorizations') {
+        auth = Rack::Auth::Basic::Request.new(env)
+        halt 401 unless auth.credentials == %w[mislav kitty]
+        json [
+          {:token => 'OTOKEN', :note => 'hub', :note_url => 'http://defunkt.io/hub/'}
+        ]
+      }
+      post('/authorizations') {
+        status 422
+        json :message => "Validation Failed",
+          :errors => [{:resource => "OauthAccess", :code => "already_exists", :field => "description"}]
+      }
+      get('/user') {
+        json :login => 'mislav'
+      }
+      post('/user/repos') {
+        json :full_name => 'mislav/dotfiles'
+      }
+      """
+    When I run `hub create` interactively
+    When I type "mislav"
+    And I type "kitty"
+    Then the output should contain "github.com password for mislav (never stored):"
+    And the exit status should be 0
+    And the file "../home/.config/hub" should contain "oauth_token: OTOKEN"
+
   Scenario: Credentials from GITHUB_USER & GITHUB_PASSWORD
     Given the GitHub API server:
       """

lib/hub/github_api.rb

@@ -326,7 +326,7 @@ module Hub
           end
         end
 
-        if found = res.data.find {|auth| auth['note_url'] == oauth_app_url }
+        if found = res.data.find {|auth| auth['note'] == 'hub' || auth['note_url'] == oauth_app_url }
           found['token']
         else
           # create a new authorization