test_asyncio.test_subprocess fails with "env changed" on "AMD64 Debian root 3.x" buildbot: unclosed file <_io.FileIO name=11 mode='wb' closefd=True>

test_asyncio.test_subprocess fails with "env changed" on "AMD64 Debian root 3.x" buildbot: unclosed file <_io.FileIO name=11 mode='wb' closefd=True> #12517