New resolver: implement --user

[uranusjr]

The first three commits are from #7990.

I think the use_user_site implementation is best covered by existing tests. Let’s see what Travis thinks… if this works we should have less failing tests than in #7990.

[uranusjr]

Ah, the --user tests are skipped on Travis since their are not compatible with venv. I guess I’ll copy some tests then.

[pradyunsg]

@uranusjr I think we can drop the --use-venv from Travis CI.

[uranusjr]

I found that a lot of the tests are of poor quality anyway (most are network tests), and ended up porting them to test_new_resolver_user.py. We can use them to replace tests in test_install_user.py in the future.

[pradyunsg]

Oooooooo.

We'd need to think about how to represent "user installs" in the YAML tests.

/cc @ilanschnell

[BrownTruck]

Hello!

I am an automated bot and I have noticed that this pull request is not currently able to be merged. If you are able to either merge the master branch into this pull request or rebase this pull request against master then it will be eligible for code review and hopefully merging!