Ah, cool.  I did not know it worked that way.  `jarn.viewdoc` initially gives the same problem, but that is gone when I install Pygments next to it.  The `longtest` command of `zest.releaser` needs a working `rst2html.py` (so `docutils` package) and when I update that one and install `Pygments` there, `longtest` works too.

Seems good to report that for plone.org yes. I don't know if simply adding the Pygments egg would be sufficient there. Might be.