Update pip to 19.2.1

[pyup-bot]

This PR updates pip from 19.1.1 to 19.2.1.

Changelog

19.2

=================

Deprecations and Removals
-------------------------

- Drop support for EOL Python 3.4. (`6685 <https://github.com/pypa/pip/issues/6685>`_)
- Improve deprecation messages to include the version in which the functionality will be removed. (`6549 <https://github.com/pypa/pip/issues/6549>`_)

Features
--------

- Credentials will now be loaded using `keyring` when installed. (`5948 <https://github.com/pypa/pip/issues/5948>`_)
- Fully support using ``--trusted-host`` inside requirements files. (`3799 <https://github.com/pypa/pip/issues/3799>`_)
- Update timestamps in pip's ``--log`` file to include milliseconds. (`6587 <https://github.com/pypa/pip/issues/6587>`_)
- Respect whether a file has been marked as "yanked" from a simple repository
(see `PEP 592 <https://www.python.org/dev/peps/pep-0592/>`__ for details). (`6633 <https://github.com/pypa/pip/issues/6633>`_)
- When choosing candidates to install, prefer candidates with a hash matching
one of the user-provided hashes. (`5874 <https://github.com/pypa/pip/issues/5874>`_)
- Improve the error message when ``METADATA`` or ``PKG-INFO`` is None when
accessing metadata. (`5082 <https://github.com/pypa/pip/issues/5082>`_)
- Add a new command ``pip debug`` that can display e.g. the list of compatible
tags for the current Python. (`6638 <https://github.com/pypa/pip/issues/6638>`_)
- Display hint on installing with --pre when search results include pre-release versions. (`5169 <https://github.com/pypa/pip/issues/5169>`_)
- Report to Warehouse that pip is running under CI if the ``PIP_IS_CI`` environment variable is set. (`5499 <https://github.com/pypa/pip/issues/5499>`_)
- Allow ``--python-version`` to be passed as a dotted version string (e.g.
``3.7`` or ``3.7.3``). (`6585 <https://github.com/pypa/pip/issues/6585>`_)
- Log the final filename and SHA256 of a ``.whl`` file when done building a
wheel. (`5908 <https://github.com/pypa/pip/issues/5908>`_)
- Include the wheel's tags in the log message explanation when a candidate
wheel link is found incompatible. (`6121 <https://github.com/pypa/pip/issues/6121>`_)
- Add a ``--path`` argument to ``pip freeze`` to support ``--target``
installations. (`6404 <https://github.com/pypa/pip/issues/6404>`_)
- Add a ``--path`` argument to ``pip list`` to support ``--target``
installations. (`6551 <https://github.com/pypa/pip/issues/6551>`_)

Bug Fixes
---------

- Set ``sys.argv[0]`` to the underlying ``setup.py`` when invoking ``setup.py``
via the setuptools shim so setuptools doesn't think the path is ``-c``. (`1890 <https://github.com/pypa/pip/issues/1890>`_)
- Update ``pip download`` to respect the given ``--python-version`` when checking
``"Requires-Python"``. (`5369 <https://github.com/pypa/pip/issues/5369>`_)
- Respect ``--global-option`` and ``--install-option`` when installing from
a version control url (e.g. ``git``). (`5518 <https://github.com/pypa/pip/issues/5518>`_)
- Make the "ascii" progress bar really be "ascii" and not Unicode. (`5671 <https://github.com/pypa/pip/issues/5671>`_)
- Fail elegantly when trying to set an incorrectly formatted key in config. (`5963 <https://github.com/pypa/pip/issues/5963>`_)
- Prevent DistutilsOptionError when prefix is indicated in the global environment and `--target` is used. (`6008 <https://github.com/pypa/pip/issues/6008>`_)
- Fix ``pip install`` to respect ``--ignore-requires-python`` when evaluating
links. (`6371 <https://github.com/pypa/pip/issues/6371>`_)
- Fix a debug log message when freezing an editable, non-version controlled
requirement. (`6383 <https://github.com/pypa/pip/issues/6383>`_)
- Extend to Subversion 1.8+ the behavior of calling Subversion in
interactive mode when pip is run interactively. (`6386 <https://github.com/pypa/pip/issues/6386>`_)
- Prevent ``pip install <url>`` from permitting directory traversal if e.g.
a malicious server sends a ``Content-Disposition`` header with a filename
containing ``../`` or ``..\\``. (`6413 <https://github.com/pypa/pip/issues/6413>`_)
- Hide passwords in output when using ``--find-links``. (`6489 <https://github.com/pypa/pip/issues/6489>`_)
- Include more details in the log message if ``pip freeze`` can't generate a
requirement string for a particular distribution. (`6513 <https://github.com/pypa/pip/issues/6513>`_)
- Add the line number and file location to the error message when reading an
invalid requirements file in certain situations. (`6527 <https://github.com/pypa/pip/issues/6527>`_)
- Prefer ``os.confstr`` to ``ctypes`` when extracting glibc version info. (`6543 <https://github.com/pypa/pip/issues/6543>`_, `6675 <https://github.com/pypa/pip/issues/6675>`_)
- Improve error message printed when an invalid editable requirement is provided. (`6648 <https://github.com/pypa/pip/issues/6648>`_)
- Improve error message formatting when a command errors out in a subprocess. (`6651 <https://github.com/pypa/pip/issues/6651>`_)

Vendored Libraries
------------------

- Upgrade certifi to 2019.6.16
- Upgrade distlib to 0.2.9.post0
- Upgrade msgpack to 0.6.1
- Upgrade requests to 2.22.0
- Upgrade urllib3 to 1.25.3
- Patch vendored html5lib, to prefer using `collections.abc` where possible.

Improved Documentation
----------------------

- Document how Python 2.7 support will be maintained. (`6726 <https://github.com/pypa/pip/issues/6726>`_)
- Upgrade Sphinx version used to build documentation. (`6471 <https://github.com/pypa/pip/issues/6471>`_)
- Fix generation of subcommand manpages. (`6724 <https://github.com/pypa/pip/issues/6724>`_)
- Mention that pip can install from git refs. (`6512 <https://github.com/pypa/pip/issues/6512>`_)
- Replace a failing example of pip installs with extras with a working one. (`4733 <https://github.com/pypa/pip/issues/4733>`_)

Links

• PyPI: https://pypi.org/project/pip
• Changelog: https://pyup.io/changelogs/pip/
• Homepage: https://pip.pypa.io/