* person starts typing "abcd"
* request for user "abcd" is sent to server
* person continues typing "ef"
* request for user "abcdef" is sent to server
* response for user "abcdef" arrives, icon for user "abcdef" is shown
* response for user "abcd" arrives, icon for user "abcd" was shown –
with this commit, this response is ignored instead
This is not just "showing the wrong avatar", btw: `MkSignin` uses the
`user` variable to decide whether to use 2FA, so having the wrong data
in user can make a login attempt fail.
5af38db74b