Prerequisites: have two accounts online.

Steps:

1. Chat → Add contact…;
2. Enter a valid identifier, and hit Tab;
3. Replace the automatically-set alias in the Alias field with something of your own choosing;
4. Realise you're using the wrong account, and change the Account selector.

Expected result:

The account changes, and nothing else changes.

Actual result:

The account changes, and the contact's alias is fetched from the CM and replaces my lovingly hand-entered alias for the contact. I think this should only happen if the alias hasn't been manually altered.