It'd be helpful to be allowed to merge reviews in the case that multiple
reviews are created (instead of updated) but related. The case this may
happen might be through an automated tool that creates post-review reviews
and the user forgot to check-in changes the first time, so upon checking-in a
second change, an additional review is created when they were related to the
first review.
Another alternative would be to allow the post-review to take an additional
external ID (such as a JIRA issue number) during creation. Then we can
update reviews based upon the external ID instead of merging (but that may be
helpful regardless).
