mod_roster_command: Fix subscription when the "user JID" is a bare domain. Do not attempt to update the roster when the user is bare domain (e.g. a component), since they don't have rosters and the attempt results in an error: $ prosodyctl mod_roster_command subscribe proxy.example.com contact@example.com xxxxxxxxxxFailed to execute command: Error: /usr/lib/prosody/core/rostermanager.lua:104: attempt to concatenate local 'username' (a nil value) stack traceback: /usr/lib/prosody/core/rostermanager.lua:104: in function 'load_roster' /usr/lib/prosody/core/rostermanager.lua:305: in function 'set_contact_pending_out' mod_roster_command.lua:44: in function 'subscribe'

---
labels:
- Stage-Alpha
...

Introduction
============

This is an experimental authentication module that does an asynchronous
HTTP call to verify username and password.

Details
=======

When a user attempts to authenticate to Prosody, this module takes the
username and password and does a HTTP GET request with [Basic
authentication][rfc7617] to the configured `http_auth_url`.

Configuration
=============

``` lua
VirtualHost "example.com"
authentication = "http_async"
http_auth_url = "http://example.com/auth"
```

Compatibility
=============

Requires Prosody trunk