Improve performance of checking whether diffsets exist.
Review Request #12853 — Created Feb. 28, 2023 and submitted — Latest diff uploaded
Some review request actions need to check whether the current review
request has any diffsets. This was initially done by checking directly
on the diffset history, but there are some shortcuts we can take in this
computation based on various caches. This change adds a new
has_diffsetsproperty for this purpose.
Ran unit tests.