Federation: history is broken when an invited member joins a room that he left previously

[matrixbot]

This issue has been migrated from #3515.

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TL;DR: history may be missing between a federated user being re-invited to a room and re-joining it.

Description

A part of the room history is missing when an invited member joins a room that he left previously,
if the room has been created on another homeserver than the member's one.
Note: The e2e encryption is disabled in this room.

Steps to reproduce

• Consider 2 users userA and userB, created on 2 different Homeservers.
• userA creates a room, history_visibility is shared (default value)
• userA invites userB
• userA sends some messages
• userB joins, he can read the messages OK
• userA and userB send some messages OK
• userB leaves the room
• userA sends a message M1
• userA invites again userB
• userA sends a message M2
• userB joins, the messages M1 and M2 are missing in the room history (I checked we did not get them in the server sync response after userB joined the room) NOK

Note1: The room history is restored correctly if we trigger an initial sync. Indeed the messages M1 and M2 are then provided in the server sync response.

Note2: You can send more than 1 message with the message M2. The problem is the same, userB don't receive them when he joins. He gets them only by triggering an initial sync.

Note3: This issue is not reproduced when userA and userB belong to the same homeserver.

[bkil]

Possibly related #15717