Patch by Charles-Axel Dein.

Patch from Donald Stufft.

This is basically a backport of issues #9003 and #22366.

The backport currently doesn't achieve anything since the function isn't used (yet).

daemon threads run while the interpreter is shutting down; instead,
these threads are now killed when they try to take the GIL), as it seems
to break some existing code.

The backport of ensurepip to 2.7.9 allows pip to optionally be installed
or upgraded using the bundled pip provided by the new ensurepip module.
The option can be specified persistently using the configure option:

    ./configure --with-ensurepip[=upgrade|install|no]

It can also be overridden on either the "install" or "altinstall" targets:

    make [alt]install ENSUREPIP=[upgrade|install|no]

For Python 2, the default option is "no" (do not install pip).

Warn against the use of leaking macro PyObject_REPR().

Patch by Roumen Petrov.

Fixed an error in _PySys_GetSizeOf declaration.

* Backports ensurepip to the 2.7 branch
* Backports some of the improved documentation to the 2.7 branch.
* Adds a private backport of the 3.x mock library as test._mock_backport
  to enable saner testing of ensurepip.

Key Differences from 3.x:

* Ensurepip does not have any Makefile integration, specifically
  it is not ran by default in the Makefile.
* There is no venv module in 2.7, so downstream distributors can
  completely disable ensurepip, ideally with a message redirecting
  to the correct way to install pip.
* To match the ``python`` command in 2.7, ensurepip will install
  the unversioned ``pip`` command as well.
* No-op and hide --default-pip and add --no-default-pip to restore
  the 3.x behavor on 2.7.