[Checkins] [zopefoundation/Zope] 9e5a57: Forward port of #839 (#842)

[Dieter Maurer]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/Zope
  Commit: 9e5a57925275bbfa28d0c40047ada71bb74da8cb
      https://github.com/zopefoundation/Zope/commit/9e5a57925275bbfa28d0c40047ada71bb74da8cb
  Author: Dieter Maurer <d-maurer at users.noreply.github.com>
  Date:   2020-06-03 (Wed, 03 Jun 2020)

  Changed paths:
    M CHANGES.rst
    M constraints.txt
    M requirements-full.txt
    M src/Products/PageTemplates/engine.py
    A src/Products/PageTemplates/tests/testErrorHandling.py
    M versions-prod.cfg

  Log Message:
  -----------
  Forward port of #839 (#842)

Improve information for errors during template execution (#839)
* Use `chameleon>=3.7.2` configuration to obtain better information for errors during template execution; fixes #837