admin can't join a guest-user to a channel via API, if he(admin) isn't in that channel

[maxdwit]

Rocket.Chat Version: 0.50.0 ( Ubuntu/snapd)
Running Instances: 1
DB Replicaset OpLog: disabled
Node Version: v4.6.2

admin with full rights can't join a user to a channel via API, if he (the admin) isn't in the channel.

Guest role: create-d / view-I-room ( nothing else)
Steps:

1. login as admin via api/v1/login as admin. Token and userID is used for subsequent steps
2. create a user via API whilst putting him into the role "guest". verified=yes, joinDefaultChannels=false
3. Read _id from channel "test" via API channels.list. This is a not protected/private chat.
4. call channels.invite with userid, channelid
   { "success": false, "error": "Not allowed [error-not-allowed]", "errorType": "error-not-allowed" }
   Second test:
5. logged in as administrator via api
6. read _id from channel "test" via API channels.list.
7. invited user "admin" whos is currently logged in via api to a channel.
8. This worked.

Expected behaviour: admin can join any user to a channel and/or private channel.

I did not test what would happen if I a new created user is in the group "user", as this is no use case for me.

[MartinSchoeler]

duplicate of #5683