JID displayed instead of nickname in ConversationTab in history

Steps to reproduce

• Open ConversationTab (1:1 chat) with somebody you have an archive with.
• PageUp

Observed behaviour

If your contact is foo@foobar.com with nick foo, and you are bar@foobar.com with nick bar, then the chat appears like the following:

<datetime> foo@foobar.com: a

<datetime> bar@foobar.com: b

<time> foo: c

<time> bar: d