Update pip to 18.0

[pyup-bot]

This PR updates pip from 10.0.1 to 18.0.

Changelog

18.0

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

Process
-------

- Switch to a Calendar based versioning scheme.
- Formally document our deprecation process as a minimum of 6 months of deprecation
warnings.
- Adopt and document NEWS fragment writing style.
- Switch to releasing a new, non bug fix version of pip every 3 months.

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

- Remove the legacy format from pip list. (3651, 3654)
- Dropped support for Python 3.3. (3796)
- Remove support for cleaning up egg fragment postfixes. (4174)
- Remove the shim for the old get-pip.py location. (5520)

For the past 2 years, it's only been redirecting users to use the newer
https://bootstrap.pypa.io/get-pip.py location.

Features
--------

- Introduce a new --prefer-binary flag, to prefer older wheels over newer source packages. (3785)
- Improve autocompletion function on file name completion after options
which have ``<file>``, ``<dir>`` or ``<path>`` as metavar. (4842, 5125)
- Add support for installing PEP 518 build dependencies from source. (5229)
- Improve status message when upgrade is skipped due to only-if-needed strategy. (5319)

Bug Fixes
---------

- Update pip's self-check logic to not use a virtualenv specific file and honor cache-dir. (3905)
- Remove compiled pyo files for wheel packages. (4471)
- Speed up printing of newly installed package versions. (5127)
- Restrict install time dependency warnings to directly-dependant packages. (5196, 5457)

Warning about the entire package set has resulted in users getting confused as
to why pip is printing these warnings.
- Improve handling of PEP 518 build requirements: support environment markers and extras. (5230, 5265)
- Remove username/password from log message when using index with basic auth. (5249)
- Remove trailing os.sep from PATH directories to avoid false negatives. (5293)
- Fix "pip wheel pip" being blocked by the "don't use pip to modify itself" check. (5311, 5312)
- Disable pip's version check (and upgrade message) when installed by a different package manager. (5346)

This works better with Linux distributions where pip's upgrade message may
result in users running pip in a manner that modifies files that should be
managed by the OS's package manager.
- Check for file existence and unlink first when clobbering existing files during a wheel install. (5366)
- Improve error message to be more specific when no files are found as listed in as listed in PKG-INFO. (5381)
- Always read ``pyproject.toml`` as UTF-8. This fixes Unicode handling on Windows and Python 2. (5482)
- Fix a crash that occurs when PATH not set, while generating script location warning. (5558)
- Disallow packages with ``pyproject.toml`` files that have an empty build-system table. (5627)

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

- Update CacheControl to 0.12.5.
- Update certifi to 2018.4.16.
- Update distro to 1.3.0.
- Update idna to 2.7.
- Update ipaddress to 1.0.22.
- Update pkg_resources to 39.2.0 (via setuptools).
- Update progress to 1.4.
- Update pytoml to 0.1.16.
- Update requests to 2.19.1.
- Update urllib3 to 1.23.

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

- Document how to use pip with a proxy server. (512, 5574)
- Document that the output of pip show is in RFC-compliant mail header format. (5261)

Links

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

[codecov]

Codecov Report

Merging #9 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #9   +/-   ##
=======================================
  Coverage   88.54%   88.54%           
=======================================
  Files           6        6           
  Lines         358      358           
=======================================
  Hits          317      317           
  Misses         41       41

[pyup-bot]

Closing this in favor of #39