Just narrowed it down a bit further, and the issue also exists in 2.1.0, so that should help isolate the change in behavior as being introduced in the upgrade from 2.0.2 to 2.1.0.
The bugfix that I am waiting for is under this issue. It is fairly specialized to using interpolators to constrain behaviors in plots.
https://discourse.bokeh.org/t/bokeh-plotting-changes-between-2-0-2-and-2-1-x/6004
Bokeh has a detailed list of what goes into each release, separated into bugfixes, features, tasks, etc. See the release summary here https://docs.bokeh.org/en/latest/docs/releases.html. At that URL, there are also links for detailed changelogs.