Usercards don't show shortnames when switched directly

[anon42064797]

Repro steps:

1. Click on someone’s avatar
2. Click on a different avatar

You’ll see a usercard without a shortname:

Same thing also applies to mention links et al.

This does not happen when dismissing the first usercard before opening the second one.

[DeanMarkTaylor (Dean Taylor)]

Visual example of the username not displaying:

[fantasticfears (Erick Guan)]

My fault for not adding a property. Fix here:

https://github.com/discourse/discourse/pull/3499