Suppress duplicate joins

[matrixbot]

Created by @ matthew:matrix.org.

[ara4n]

This sort of thing just makes us look crap ^

[kegsay]

I would argue this is not the responsibility of clients to suppress. If this were done server-side, all clients would benefit from having dupes suppressed. We don't want to suppress dupe joins over federation for reasons I forget. However, servers have no reason to expose this aberration to clients.

[erikjohnston]

It looks like we do currently suppress sequential duplicate joins, which I think might be new behaviour on synapse? We would still probably get duplicate joins if someone tried to join the same room multiple times at once.

[ara4n]

so yes, this happens when people get bored of a join completing and so hit join twice - i.e. "try to join the same room multiple times at one". @erikjohnston is there any hope of suppressing this?

[ara4n]

spotted this happening in matrix-org/synapse#700. @erikjohnston please yell if i shouldn't have closed it.