Patch by Xiang Zhang.

Patch by Xiang Zhang.

If they aren't present, set them to an empty string.

Issue #26804: urllib.request will prefer lower_case proxy environment variables
over UPPER_CASE or Mixed_Case ones.

Patch contributed by Hans-Peter Jansen. Reviewed by Martin Panter and Senthil Kumaran.

over UPPER_CASE or Mixed_Case ones.

Patch contributed by Hans-Peter Jansen. Reviewed by Martin Panter and Senthil Kumaran.

Reported by Saul Spatz on docs@

Minimal supported Tcl/Tk version is 8.4, and this is checked in _tkinter.c.

differing items (like bytes in the -b mode).  This affects assertListEqual()
and assertTupleEqual().

There were duplicated methods with the same name and body.

It is not needed since tests use unittest.main().

Optimizations section.

reopened on Windows.  Added tests for fallbacks.

reopened on Windows.  Added tests for fallbacks.

Patch by Jon Dufresne.

We will keep platform.dist() and platform.linux_distribution() to make porting
from Python 2 easier.

Patch by Kumaripaba Miyurusara Athukorala.

We will keep platform.dist() and platform.linux_distribution() to make porting
from Python 2 easier.

Patch by Kumaripaba Miyurusara Athukorala.

See https://mail.python.org/pipermail/python-legal-sig/2013-November/000059.html
for details.

Patch by Antoine Pitrou.

See https://mail.python.org/pipermail/python-legal-sig/2013-November/000059.html
for details.

Patch by Antoine Pitrou.

Patch by Corey Brune.

Patch by Corey Brune.

All signal.SIG* constants may not be defined on Windows so a call like

    signal.signal(signal.SIGPIPE, lambda signum, frame: sys.exit(1))

will raise an AttributeError.