breakup pip pull request 511

gistfile1.txt

break up https://github.com/pypa/pip/pull/511

part1: MERGED https://github.com/pypa/pip/pull/548
  - system_site_packages option for reset_env
  - pypi_server.PyPIProxy.setup() occur in a sitecustomize file (not pth file) to prevent pkg_resources.working_set corruption that corrupts the sys.path

part2: MERGED https://github.com/pypa/pip/pull/553
  - migrate existing tests to new test_user_site.py module

part3: MERGED https://github.com/pypa/pip/pull/567
  - 493: pip shouldn't allow --user installs in virtualenvs (w/o --system-site-packages)

part4: MERGED https://github.com/pypa/pip/pull/574
  - 440: pip install --user tries to uninstall system package

part5: MERGED https://github.com/pypa/pip/pull/576
  - generic way to pass in sitecustomize snippets (e.g. for patching) in to reset_env

part6: MERGED https://github.com/pypa/pip/pull/585
  - 573: don't --user install in --system_site_packages virtualenvs when a conflict is present in the virtualenv site.

part7:  https://github.com/pypa/pip/pull/595
  - 494: can't uninstall --user "develop" install
  - update the news with the user facing changes

SGTM

@qwcode you also want part8 add overview to docs/news.txt and yourself to AUTHORS.txt if not done already.