When we load the diff viewer, we include the latest activity timestamp

in the page data. This is then used with subsequent accesses to the

last-update resource to determine whether to show the updates bubble.
The timestamp of a draft diffset was being included in the initial

activity timestamp, while it is not included in the timestamp returned

by the API. This meant that the updates bubble would pop up saying the

diff was new because the timestamp did not match.

Loaded the diff viewer with a draft diff (while viewing as an admin

user). Saw that the updates bubble no longer popped up incorrectly.