For those, who are using Robot Framework for acceptance testing:
The current Plone versions.cfg pins
robotframework = 2.7.7 and
robotsuite = 1.3.3, which is a good working combination.
However, if you are using a newer version Robot Framework for some reason (e.g.
>= 2.8.0), you should pin
robotframework = 2.8.4
robotsuite = 1.5.0
(or newer robotsuite, when such is released).
The newest Robot Framework release 2.8.5 introduced a feature that conflicts with Zope DateTime-library and the Robot Framework team said that they cannot fix the issue for 2.8.x releases, so the next new Zope-compatible Robot Framework version after 2.8.4 could be 2.9.0 (whenever it's released).