Incoming MUC-PMs: Ignore `received` carbons
Versions
- OS: Ubuntu 18.04
- Gajim version: 1.0.3 (flatpak)
- GTK version: 3.2.8?
- Python-nbxmpp version: ?
Steps to reproduce the problem
- Open a whisper chat with Conversations
- Chat there with Conversations and Dino (or probably by anything else than Gajim)
- Look at Gajim or open it.
Expected behavior
I see the whispered MUC PM in Gajim with every message appearing only once.
Actual behavior
I see every received line three times.
I originally said this in comment of #8524 (comment 187895) .