V4.beta.2 missing transition for progress-bar

Created by: tmorehouse

It appears that https://github.com/twbs/bootstrap/pull/22703 quietly removed the default transition CSS for .progress-bar: https://github.com/twbs/bootstrap/pull/22703/files#diff-2afc93127d8c7692f4efec8bedb49bb3L22

Just wondering if this was a mistake, or intentional.