Specify redirect to root, otherwise it will go to HTTP_REFERER

Which in the test for some reason is set to the same authorize path that was just POSTed to

test/integration/omniauth_test.rb

@@ -137,7 +137,7 @@ def setup
           assert_nil session[:user_id]
 
           # AAI
-          post omniauth_authorize_path(:elixir_aai)
+          post omniauth_authorize_path(:elixir_aai, state: 'return_to:/')
           follow_redirect!
           assert_redirected_to root_path
           assert_equal existing_user.id, session[:user_id]