Message 343633 - Python tracker

This issue has been fixed in 36763 by the PEP 587 which provides a new "Isolated Configuration" and a way to tune the Python configuration without impacting subprocesses. For example, the Isolated Configuration ignores environment variables by default.

In Python 3.7 and older, you can set Py_IgnoreEnvironmentFlag to 1 (the flag exists also in Python 2.7), or even set Py_IsolatedFlag to 1 (new in Python 3.4).