From 97bec8ecf213e065f1da2e1f783c99abbb1a4332 Mon Sep 17 00:00:00 2001
From: Pradyun Gedam <pradyunsg@gmail.com>
Date: Tue, 19 May 2026 08:03:08 -0700
Subject: [PATCH 1/2] Pass `-E` to subprocesses from `check_add_python_opts`

Avoid the runtime environment from affecting the tests' behaviours,
which notably checks the warning filters which can be controlled by
various environment variables.
---
 Lib/test/test_regrtest.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index 02f6e0c74b5ce8..45c05242537632 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -2277,7 +2277,7 @@ def test_python_opts(self):
 
         # Use directly subprocess to control the exact command line
         cmd = [sys.executable,
-               "-m", "test", option,
+               "-E", "-m", "test", option,
                f'--testdir={self.tmptestdir}',
                testname]
         proc = subprocess.run(cmd,

From fb82f0c7c2bdc09cd0b58d12288bfb60045d8cac Mon Sep 17 00:00:00 2001
From: Pradyun Gedam <pradyunsg@gmail.com>
Date: Tue, 19 May 2026 08:10:31 -0700
Subject: [PATCH 2/2] Add blurb

---
 .../next/Tests/2026-05-19-08-10-20.gh-issue-150046.MndDD8.rst    | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Tests/2026-05-19-08-10-20.gh-issue-150046.MndDD8.rst

diff --git a/Misc/NEWS.d/next/Tests/2026-05-19-08-10-20.gh-issue-150046.MndDD8.rst b/Misc/NEWS.d/next/Tests/2026-05-19-08-10-20.gh-issue-150046.MndDD8.rst
new file mode 100644
index 00000000000000..b322922e108690
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2026-05-19-08-10-20.gh-issue-150046.MndDD8.rst
@@ -0,0 +1 @@
+Avoid ``PYTHON*`` environment variables affecting regrtest's own tests.