Use checkout of RestrictedPython.

[icemac]

This hopefully fixed Python 3.9.

[icemac]

Python 3.9 still fails in some template tests. I cannot run the tests on Python 3.9 locally even though I have 3.9.0a5 installed: When calling tox -epy39 I get lots of errors that the Zope distribution cannot be found. I end up with over 100 test failures instead of the 6 ones TravisCI finds.

Does anyone have an idea to fix this locally without enforcing #791?

[dataflake]

I see no such issues in my local setup. tox -epy39 ran as expected and produced the same failures you see on Travis.

[icemac]

I found a way to fix my local issue: Run bin/tox -epy39 after installing virtualenv in the local venv. Now I get the same errors as TravisCI. I'll try to look into this issue later.

[dataflake]

Just did a cross-check with a fresh clone and everything is fine, apart from those six failures. This is how I create my sandbox:

git clone ...
cd Zope
python3.7 -m venv .
bin/pip install -U pip setuptools zc.buildout virtualenv wheel
bin/buildout
bin/tox

[icemac]

@dataflake My setup is quite close to yours. Thank you.

[icemac]

I'd like to merge this PR so the tests on Python 3.9 can get green. (With this PR they fail with AssertionError: Template errors: ['Compilation failed', 'builtins.SyntaxError: invalid syntax in a single test.)

As Zope 5 final ist to be released before the final Python 3.9 release (September vs. October 2020), I see no need to have a release of RestrictedPython supporting Python 3.9 before the Zope 5 release.

[dataflake]

LGTM