Fix a bug with the revision selector for file attachments.
Review Request #13119 — Created June 21, 2023 and submitted — Latest diff uploaded
There was a bug with the revision selector for file attachments, where the
grey bar of the selector range would disappear when interdiffs were selected.
The problem came from improperly setting the list that stored our diff values.
Played around with the selector, diffing between the original and revisions,
with interdiffs and saw that the grey bar always appeared correctly.