Matrix notifications failed for anyone who entered a room alias. The send
endpoint only accepts a room ID, and an unresolved alias broke the request
outright: the leading "#" opens a URI fragment, so the PUT landed on
/_matrix/client/v3/rooms/ instead of the send endpoint. Element shows users
the alias, so this is the value most people paste in.
- Resolve "#alias:server" through GET /_matrix/client/v3/directory/room/{alias}
before sending, per the client-server spec
- Percent-encode the room ID in the send path; ":" was previously sent raw
- Strip trailing slashes from the homeserver URL to avoid "//_matrix/..."
Alias resolution failures return false and log, matching how the provider
already handles send failures.
Closes#3478
Alex Holliday
egeoztass