fix an issue with prop picking

The closest depth was never being updated resulting in incorrect actors be listed as the closest and the PickedZ being incorrect.

Do: test

This merge request has been queued for testing. Test results may be viewed on:

• CDash (master)
• Buildbot (master) (only visible from inside Kitware)

Branch-at-master: d426294a

Do: merge

merged

mentioned in commit 70b780f9

mentioned in merge request !6351 (closed)