Users 'People' sidebar list shows multiple entries after HipChat Server upgrade to v2.2.8

Summary

After upgrading to HipChat Server v2.2.8 (and rebooting), seemingly random 1-1 chats in the 'People' section of the sidebar are added to users client (sidebar is also called the autojoin list) and are repopulated on client reconnection.

Environment

HipChat Server v2.2.8
HipChat Server v2.2.7

Steps to Reproduce

1. Create two users on the HipChat Server, both open with zero private chats.
2. User 1 adds User 2 to their sidebar list without sending a message.

Expected Results

User 2 does not see User 1 added to their sidebar, even on reconnection.

Actual Results

If User 2 reconnects, User 1 is shown in their sidebar list, even though no messages were sent between the two users.

Notes

There are unconfirmed reports of 'Rooms' also showing the same behavior as the 'People' section in the sidebar, however these have yet to be duplicated.

Workaround

No workaround presently

Resolution

Upgrade to version 2.2.9 of HipChat Server, which was released to production on January 23, 2018