See on Travis CI: https://travis-ci.org/python/cpython/jobs/223771666
Warning -- sys.path was modified by test_site
Before: (47345855849656, ['', '/usr/local/lib/python37.zip', '/home/travis/build/python/cpython/Lib', '/home/travis/build/python/cpython/build/lib.linux-x86_64-3.7-pydebug'], ['', '/usr/local/lib/python37.zip', '/home/travis/build/python/cpython/Lib', '/home/travis/build/python/cpython/build/lib.linux-x86_64-3.7-pydebug'])
After: (47345855849656, ['', '/usr/local/lib/python37.zip', '/home/travis/build/python/cpython/Lib', '/home/travis/build/python/cpython/build/lib.linux-x86_64-3.7-pydebug'], ['', '/usr/local/lib/python37.zip', '/home/travis/build/python/cpython/Lib', '/home/travis/build/python/cpython/build/lib.linux-x86_64-3.7-pydebug', '/home/travis/.local/lib/python3.7/site-packages'])