Update pip to 19.3

[pyup-bot]

This PR updates pip from 19.2.3 to 19.3.

Changelog

19.3

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

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

- Remove undocumented support for un-prefixed URL requirements pointing
to SVN repositories. Users relying on this can get the original behavior
by prefixing their URL with ``svn+`` (which is backwards-compatible). (`7037 <https://github.com/pypa/pip/issues/7037>`_)
- Remove the deprecated ``--venv`` option from ``pip config``. (`7163 <https://github.com/pypa/pip/issues/7163>`_)

Features
--------

- Print a better error message when ``--no-binary`` or ``--only-binary`` is given
an argument starting with ``-``. (`3191 <https://github.com/pypa/pip/issues/3191>`_)
- Make ``pip show`` warn about packages not found. (`6858 <https://github.com/pypa/pip/issues/6858>`_)
- Support including a port number in ``--trusted-host`` for both HTTP and HTTPS. (`6886 <https://github.com/pypa/pip/issues/6886>`_)
- Redact single-part login credentials from URLs in log messages. (`6891 <https://github.com/pypa/pip/issues/6891>`_)
- Implement manylinux2014 platform tag support.  manylinux2014 is the successor
to manylinux2010.  It allows carefully compiled binary wheels to be installed
on compatible Linux platforms.  The manylinux2014 platform tag definition can
be found in `PEP599 <https://www.python.org/dev/peps/pep-0599/>`_. (`7102 <https://github.com/pypa/pip/issues/7102>`_)

Bug Fixes
---------

- Abort installation if any archive contains a file which would be placed
outside the extraction location. (`3907 <https://github.com/pypa/pip/issues/3907>`_)
- pip's CLI completion code no longer prints a Traceback if it is interrupted. (`3942 <https://github.com/pypa/pip/issues/3942>`_)
- Correct inconsistency related to the ``hg+file`` scheme. (`4358 <https://github.com/pypa/pip/issues/4358>`_)
- Fix ``rmtree_errorhandler`` to skip non-existing directories. (`4910 <https://github.com/pypa/pip/issues/4910>`_)
- Ignore errors copying socket files for local source installs (in Python 3). (`5306 <https://github.com/pypa/pip/issues/5306>`_)
- Fix requirement line parser to correctly handle PEP 440 requirements with a URL
pointing to an archive file. (`6202 <https://github.com/pypa/pip/issues/6202>`_)
- The ``pip-wheel-metadata`` directory does not need to persist between invocations of pip, use a temporary directory instead of the current ``setup.py`` directory. (`6213 <https://github.com/pypa/pip/issues/6213>`_)
- Fix ``--trusted-host`` processing under HTTPS to trust any port number used
with the host. (`6705 <https://github.com/pypa/pip/issues/6705>`_)
- Switch to new ``distlib`` wheel script template. This should be functionally
equivalent for end users. (`6763 <https://github.com/pypa/pip/issues/6763>`_)
- Skip copying .tox and .nox directories to temporary build directories (`6770 <https://github.com/pypa/pip/issues/6770>`_)
- Fix handling of tokens (single part credentials) in URLs. (`6795 <https://github.com/pypa/pip/issues/6795>`_)
- Fix a regression that caused ``~`` expansion not to occur in ``--find-links``
paths. (`6804 <https://github.com/pypa/pip/issues/6804>`_)
- Fix bypassed pip upgrade warning on Windows. (`6841 <https://github.com/pypa/pip/issues/6841>`_)
- Fix 'm' flag erroneously being appended to ABI tag in Python 3.8 on platforms that do not provide SOABI (`6885 <https://github.com/pypa/pip/issues/6885>`_)
- Hide security-sensitive strings like passwords in log messages related to
version control system (aka VCS) command invocations. (`6890 <https://github.com/pypa/pip/issues/6890>`_)
- Correctly uninstall symlinks that were installed in a virtualenv,
by tools such as ``flit install --symlink``. (`6892 <https://github.com/pypa/pip/issues/6892>`_)
- Don't fail installation using pip.exe on Windows when pip wouldn't be upgraded. (`6924 <https://github.com/pypa/pip/issues/6924>`_)
- Use canonical distribution names when computing ``Required-By`` in ``pip show``. (`6947 <https://github.com/pypa/pip/issues/6947>`_)
- Don't use hardlinks for locking selfcheck state file. (`6954 <https://github.com/pypa/pip/issues/6954>`_)
- Ignore "require_virtualenv" in ``pip config`` (`6991 <https://github.com/pypa/pip/issues/6991>`_)
- Fix ``pip freeze`` not showing correct entry for mercurial packages that use subdirectories. (`7071 <https://github.com/pypa/pip/issues/7071>`_)
- Fix a crash when ``sys.stdin`` is set to ``None``, such as on AWS Lambda. (`7118 <https://github.com/pypa/pip/issues/7118>`_, `7119 <https://github.com/pypa/pip/issues/7119>`_)

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

- Upgrade certifi to 2019.9.11
- Add contextlib2 0.6.0 as a vendored dependency.
- Remove Lockfile as a vendored dependency.
- Upgrade msgpack to 0.6.2
- Upgrade packaging to 19.2
- Upgrade pep517 to 0.7.0
- Upgrade pyparsing to 2.4.2
- Upgrade pytoml to 0.1.21
- Upgrade setuptools to 41.4.0
- Upgrade urllib3 to 1.25.6

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

- Document caveats for UNC paths in uninstall and add .pth unit tests. (`6516 <https://github.com/pypa/pip/issues/6516>`_)
- Add architectural overview documentation. (`6637 <https://github.com/pypa/pip/issues/6637>`_)
- Document that ``--ignore-installed`` is dangerous. (`6794 <https://github.com/pypa/pip/issues/6794>`_)

Links

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