Build the OAuth redirect URL ourselves, rather than relying on undocumented Flask behavior

app.py

@@ -2,6 +2,7 @@ import logging
 import os
 import json
 
+from functools import partial
 from flask import Flask, request, Request, _request_ctx_stack
 from flask.ext.principal import Principal
 from flask.ext.login import LoginManager, UserMixin
@@ -21,6 +22,7 @@ from data.buildlogs import BuildLogs
 from data.archivedlogs import LogArchive
 from data.userevent import UserEventsBuilderModule
 from data.queue import WorkQueue, MetricQueueReporter
+from util import get_app_url
 from util.saas.analytics import Analytics
 from util.saas.exceptionlog import Sentry
 from util.names import urn_generator
@@ -173,5 +175,4 @@ class LoginWrappedDBUser(UserMixin):
   def get_id(self):
     return unicode(self._uuid)
 
-def get_app_url():
-  return '%s://%s' % (app.config['PREFERRED_URL_SCHEME'], app.config['SERVER_HOSTNAME'])
+get_app_url = partial(get_app_url, app.config)