Edited messages appear twice in fulltext search

[matrixbot]

This issue was originally created by @S7evinK at matrix-org/dendrite#3358.

When a message is edited, they appear twice in the results of /search.
While Element Web seems to aggregate the results and only returns one results, Element Android returns both. This may be a bit confusing.

IMO, Dendrite should only return the latest message.

The responsible code for this:
https://github.com/matrix-org/dendrite/blob/14a6c100977be6484eec419fdc8f496eb27b0677/syncapi/consumers/roomserver.go#L593-L627

We'd need to check if m.relates.to in content contains a rel_type of m.replace and then delete the event_id from the fulltext index before indexing the new event.

[matrixbot]

This comment was originally posted by @adnull at matrix-org/dendrite#3358 (comment).

Hi! I'd like to take this.

[matrixbot]

This comment was originally posted by @S7evinK at matrix-org/dendrite#3358 (comment).

Sure, go for it! :)

[matrixbot]

This comment was originally posted by @S7evinK at matrix-org/dendrite#3358 (comment).

Fixed with #3363.