Merge branch 'redis-session-expire-delay' into 'master'

Fix reading session_expire_delay

The error occurs when application settings are not yet created and migrations are not yet done.

See merge request !1268

config/initializers/session_store.rb

@@ -2,7 +2,12 @@
 
 require 'gitlab/current_settings'
 include Gitlab::CurrentSettings
-Settings.gitlab['session_expire_delay'] = current_application_settings.session_expire_delay
+
+# allow it to fail: it may to do so when create_from_defaults is executed before migrations are actually done
+begin
+  Settings.gitlab['session_expire_delay'] = current_application_settings.session_expire_delay
+rescue
+end
 
 Gitlab::Application.config.session_store(
   :redis_store, # Using the cookie_store would enable session replay attacks.