Invitations not sent when added meetings from Android and Gnome

[allgood]

Steps to reproduce

1. configure DAVDroid or Gnome Online Accounts to connect to a Calendar on nextcloud
2. add a new meeting with at least one other mandatory participant

Expected behaviour

Mail invites should be sent to participants

Actual behaviour

No message is sent

Server configuration

Operating system: Debian Stretch

Web server: Apache

Database: MariaDB

PHP version: 7.0

Nextcloud version: 10.0

I've researched this problem and noted that it is because when connecting from Gnome Online Accounts or DAVDroid apps/dav/appinfo/v2/remote.php isn't executed, and v1/caldav.php is executed in its place. Digging a little more I've found that on caldav.php the plugins for invites aren't loaded.

I've made it work with a two line changes:

--- nextcloud/apps/dav/appinfo/v1/caldav.php    2016-08-25 03:59:50.000000000 -0300
+++ nextcloud-imip/apps/dav/appinfo/v1/caldav.php   2016-09-21 14:23:36.251450162 -0300
@@ -78,6 +78,8 @@
 }

 $server->addPlugin(new \Sabre\CalDAV\ICSExportPlugin());
+$server->addPlugin(new \Sabre\CalDAV\Schedule\Plugin());
+$server->addPlugin(new OCA\DAV\CalDAV\Schedule\IMipPlugin( \OC::$server->getMailer(), \OC::$server->getLogger()));
 $server->addPlugin(new ExceptionLoggerPlugin('caldav', \OC::$server->getLogger()));

 // And off we go!

After this changes, invites are sent both from Gnome and Android.

As I do not know the impact of this change on other parts of nextcloud / calendar, I am submitting this issue report.