#10713: Improve documentation for \b and \B and add a few tests.  Initial patch and tests by Martin Pool.

(Doc only.)

Patch by Mikhail Novikov.

Patch by Mikhail Novikov.

out the location of the problem. MS_WINDOWS currently implies !HAVE_WCSFTIME,
so the addition of !defined(HAVE_WCSFTIME) is for readability.

I added some tests in 2105ab8553b7 and found no bug, but it turns out
that the doctest is not actually run.  While converting the doctest to
unittest style, I stumbled upon this bug again and this time applied the
code patch provided by Filip Gruszczyński.

Issue #13521: dict.setdefault() now does only one lookup for the given key, making it "atomic" for many purposes.
Patch by Filip Gruszczyński.

Issue #13521: dict.setdefault() now does only one lookup for the given key, making it "atomic" for many purposes.
Patch by Filip Gruszczyński.