[Checkins] [zopefoundation/Zope] 9652f1: Fix ``default`` keyword handling in page templates...

[Jens Vagelpohl]

  Branch: refs/heads/4.x
  Home:   https://github.com/zopefoundation/Zope
  Commit: 9652f1ba5e28fd50e4937c931a68d48b57dfa2c2
      https://github.com/zopefoundation/Zope/commit/9652f1ba5e28fd50e4937c931a68d48b57dfa2c2
  Author: Jens Vagelpohl <jens at netz.ooo>
  Date:   2020-06-17 (Wed, 17 Jun 2020)

  Changed paths:
    M CHANGES.rst
    M src/Products/PageTemplates/engine.py
    A src/Products/PageTemplates/tests/input/Default.html
    A src/Products/PageTemplates/tests/output/Default.html
    M src/Products/PageTemplates/tests/testHTMLTests.py

  Log Message:
  -----------
  Fix ``default`` keyword handling in page templates (#847)

* - Fix ``default`` keyword handling in page templates (WIP)

* work around `chameleon`s peculiar handling of the TALES `default` value

* minor cleanup

Co-authored-by: dieter <dieter at handshake.de>