Remove unused function
Add adjuncts timestamp update helper

After fixing a problem with object caches not being correctly
invalidated we discovered a regression. Saving instance properties would
trigger the object cache system to increment the timestamp on the
instance and save it a second time. Unfortunately, it was also saving
old field values, overwriting the changes.

The solution is to fetch the object from the database before
incrementing the counter, ensuring that we do not write back stale values.
Merge pull request #1713 from jwalgran/topic/fix-cache-saving-stale-data

Fix cache saving stale data
Improve comment on `increment_adjuncts_timestamp()`
Merge pull request #1720 from RickMohr/improve-comment

Improve comment on `increment_adjuncts_timestamp()`
Merge remote-tracking branch 'origin/release'