python 3.5 sandbox deny(1) file-write-create

[gnw3]

Logwatch emails for a couple El Capitan systems had messages like:

{{{Sandbox: Python(17992) deny(1) file-write-create /opt/local/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site

Sandbox: -packages/docutils/utils/pycache/error_reporting.cpytho ...:

}}}

This happened a month ago and has not repeated but I'm wondering why it would happen at all. The files in /opt/local/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/docutils/utils/__pycache__ date from December, but the py35-cpython package was updated in March.