Update pip to 19.1

[pyup-bot]

This PR updates pip from 18.1 to 19.1.

Changelog

19.0.3

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

Bug Fixes
---------

- Fix an ``IndexError`` crash when a legacy build of a wheel fails. (`6252 <https://github.com/pypa/pip/issues/6252>`_)
- Fix a regression introduced in 19.0.2 where the filename in a RECORD file
of an installed file would not be updated when installing a wheel. (`6266 <https://github.com/pypa/pip/issues/6266>`_)

19.0.2

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

Bug Fixes
---------

- Fix a crash where PEP 517-based builds using ``--no-cache-dir`` would fail in
some circumstances with an ``AssertionError`` due to not finalizing a build
directory internally. (`6197 <https://github.com/pypa/pip/issues/6197>`_)
- Provide a better error message if attempting an editable install of a
directory with a ``pyproject.toml`` but no ``setup.py``. (`6170 <https://github.com/pypa/pip/issues/6170>`_)
- The implicit default backend used for projects that provide a ``pyproject.toml``
file without explicitly specifying ``build-backend`` now behaves more like direct
execution of ``setup.py``, and hence should restore compatibility with projects
that were unable to be installed with ``pip`` 19.0. This raised the minimum
required version of ``setuptools`` for such builds to 40.8.0. (`6163 <https://github.com/pypa/pip/issues/6163>`_)
- Allow ``RECORD`` lines with more than three elements, and display a warning. (`6165 <https://github.com/pypa/pip/issues/6165>`_)
- ``AdjacentTempDirectory`` fails on unwritable directory instead of locking up the uninstall command. (`6169 <https://github.com/pypa/pip/issues/6169>`_)
- Make failed uninstalls roll back more reliably and better at avoiding naming conflicts. (`6194 <https://github.com/pypa/pip/issues/6194>`_)
- Ensure the correct wheel file is copied when building PEP 517 distribution is built. (`6196 <https://github.com/pypa/pip/issues/6196>`_)
- The Python 2 end of life warning now only shows on CPython, which is the
implementation that has announced end of life plans. (`6207 <https://github.com/pypa/pip/issues/6207>`_)

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

- Re-write README and documentation index (`5815 <https://github.com/pypa/pip/issues/5815>`_)

19.0.1

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

Bug Fixes
---------

- Fix a crash when using --no-cache-dir with PEP 517 distributions (`6158 <https://github.com/pypa/pip/issues/6158>`_, `6171 <https://github.com/pypa/pip/issues/6171>`_)

19.0

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

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

- Deprecate support for Python 3.4 (`6106 <https://github.com/pypa/pip/issues/6106>`_)
- Start printing a warning for Python 2.7 to warn of impending Python 2.7 End-of-life and
prompt users to start migrating to Python 3. (`6148 <https://github.com/pypa/pip/issues/6148>`_)
- Remove the deprecated ``--process-dependency-links`` option. (`6060 <https://github.com/pypa/pip/issues/6060>`_)
- Remove the deprecated SVN editable detection based on dependency links
during freeze. (`5866 <https://github.com/pypa/pip/issues/5866>`_)

Features
--------

- Implement PEP 517 (allow projects to specify a build backend via pyproject.toml). (`5743 <https://github.com/pypa/pip/issues/5743>`_)
- Implement manylinux2010 platform tag support.  manylinux2010 is the successor
to manylinux1.  It allows carefully compiled binary wheels to be installed
on compatible Linux platforms. (`5008 <https://github.com/pypa/pip/issues/5008>`_)
- Improve build isolation: handle ``.pth`` files, so namespace packages are correctly supported under Python 3.2 and earlier. (`5656 <https://github.com/pypa/pip/issues/5656>`_)
- Include the package name in a freeze warning if the package is not installed. (`5943 <https://github.com/pypa/pip/issues/5943>`_)
- Warn when dropping an ``--[extra-]index-url`` value that points to an existing local directory. (`5827 <https://github.com/pypa/pip/issues/5827>`_)
- Prefix pip's ``--log`` file lines with their timestamp. (`6141 <https://github.com/pypa/pip/issues/6141>`_)

Bug Fixes
---------

- Avoid creating excessively long temporary paths when uninstalling packages. (`3055 <https://github.com/pypa/pip/issues/3055>`_)
- Redact the password from the URL in various log messages. (`4746 <https://github.com/pypa/pip/issues/4746>`_, `6124 <https://github.com/pypa/pip/issues/6124>`_)
- Avoid creating excessively long temporary paths when uninstalling packages. (`3055 <https://github.com/pypa/pip/issues/3055>`_)
- Avoid printing a stack trace when given an invalid requirement. (`5147 <https://github.com/pypa/pip/issues/5147>`_)
- Present 401 warning if username/password do not work for URL (`4833 <https://github.com/pypa/pip/issues/4833>`_)
- Handle ``requests.exceptions.RetryError`` raised in ``PackageFinder`` that was causing pip to fail silently when some indexes were unreachable. (`5270 <https://github.com/pypa/pip/issues/5270>`_, `5483 <https://github.com/pypa/pip/issues/5483>`_)
- Handle a broken stdout pipe more gracefully (e.g. when running ``pip list | head``). (`4170 <https://github.com/pypa/pip/issues/4170>`_)
- Fix crash from setting ``PIP_NO_CACHE_DIR=yes``. (`5385 <https://github.com/pypa/pip/issues/5385>`_)
- Fix crash from unparseable requirements when checking installed packages. (`5839 <https://github.com/pypa/pip/issues/5839>`_)
- Fix content type detection if a directory named like an archive is used as a package source. (`5838 <https://github.com/pypa/pip/issues/5838>`_)
- Fix listing of outdated packages that are not dependencies of installed packages in ``pip list --outdated --not-required`` (`5737 <https://github.com/pypa/pip/issues/5737>`_)
- Fix sorting ``TypeError`` in ``move_wheel_files()`` when installing some packages. (`5868 <https://github.com/pypa/pip/issues/5868>`_)
- Fix support for invoking pip using ``python src/pip ...``. (`5841 <https://github.com/pypa/pip/issues/5841>`_)
- Greatly reduce memory usage when installing wheels containing large files. (`5848 <https://github.com/pypa/pip/issues/5848>`_)
- Editable non-VCS installs now freeze as editable. (`5031 <https://github.com/pypa/pip/issues/5031>`_)
- Editable Git installs without a remote now freeze as editable. (`4759 <https://github.com/pypa/pip/issues/4759>`_)
- Canonicalize sdist file names so they can be matched to a canonicalized package name passed to ``pip install``. (`5870 <https://github.com/pypa/pip/issues/5870>`_)
- Properly decode special characters in SVN URL credentials. (`5968 <https://github.com/pypa/pip/issues/5968>`_)
- Make ``PIP_NO_CACHE_DIR`` disable the cache also for truthy values like ``"true"``, ``"yes"``, ``"1"``, etc. (`5735 <https://github.com/pypa/pip/issues/5735>`_)

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

- Include license text of vendored 3rd party libraries. (`5213 <https://github.com/pypa/pip/issues/5213>`_)
- Update certifi to 2018.11.29
- Update colorama to 0.4.1
- Update distlib to 0.2.8
- Update idna to 2.8
- Update packaging to 19.0
- Update pep517 to 0.5.0
- Update pkg_resources to 40.6.3 (via setuptools)
- Update pyparsing to 2.3.1
- Update pytoml to 0.1.20
- Update requests to 2.21.0
- Update six to 1.12.0
- Update urllib3 to 1.24.1

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

- Include the Vendoring Policy in the documentation. (`5958 <https://github.com/pypa/pip/issues/5958>`_)
- Add instructions for running pip from source to Development documentation. (`5949 <https://github.com/pypa/pip/issues/5949>`_)
- Remove references to removed ``egg=<name>-<version>`` functionality (`5888 <https://github.com/pypa/pip/issues/5888>`_)
- Fix omission of command name in HTML usage documentation (`5984 <https://github.com/pypa/pip/issues/5984>`_)

Links

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

[pyup-bot]

Closing this in favor of #58