The root message in a thread is visually separated from subsequent message the same user sends in that thread

(The title of this issue is abysmal - feel free to update it to something that makes more sense.)

When the same user sends messages in succession, Element Android will hide the username of the subsequent messages to save vertical space. It looks like this:


Element Android fails to combine a root message of a thread and subsequent messages, even if they were sent by the same user:

Reproduction steps:

1. Send a message in a room.
2. Create a thread from that message
3. Send another message in that thread.

Notice that the messages will be visually combined while sending, but after a few moments (presumably when the local echo arrives from the homeserver) the messages visually separate (a username is included for both messages).

Element Android version: 1.5.12-dev [213189342] (F-03440307) develop 03440307