[Checkins] [zopefoundation/Zope] 849b87: Improve solidity of the ``debugError`` method

[Alessandro Pisa]

  Branch: refs/heads/829-fix-debugError-4.x
  Home:   https://github.com/zopefoundation/Zope
  Commit: 849b87b4a0701881ebce13be12d788614638f8aa
      https://github.com/zopefoundation/Zope/commit/849b87b4a0701881ebce13be12d788614638f8aa
  Author: ale-rt <alessandro.pisa at gmail.com>
  Date:   2020-05-16 (Sat, 16 May 2020)

  Changed paths:
    M CHANGES.rst
    M src/ZPublisher/HTTPResponse.py
    M src/ZPublisher/tests/testHTTPResponse.py

  Log Message:
  -----------
  Improve solidity of the ``debugError`` method

Backport of #830 to the 4.x branch