[tune] debug py37 build

[richardliaw]

Why are these changes needed?

• Lint is currently failing

Related issue number

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[amogkam]

Ah nice catch! Do you know why the Python 3.6 tests don't go through the miniconda codepath? Or I guess what is if [ -n "${PYTHON-}" ] checking for?

[richardliaw]

They do go through the miniconda path. On 3.7, i think we install miniconda but don't set pip to the right miniconda pip.

On 3.6 i think we install miniconda, and we use the miniconda pip going forward.

In any case, this actually passes tests: https://travis-ci.com/github/ray-project/ray/builds/206209467

[amogkam]

@richardliaw This is great! I'm just asking so I can understand where the 3.6 and 3.7 tests diverge. Do you know where/why

On 3.7, i think we install miniconda but don't set pip to the right miniconda pip

is happening? I had spent some time trying to figure this out and from our install-dependencies script it did not seem like there should've been any pip difference between the 3.6 and 3.7 tests.

[richardliaw]

My hypothesis is that the 3.6 miniconda env has the newest version of pip but not on 3.7.

I was able to verify that after miniconda installation, the pip --version on our 3.7 was not the latest pip.

However, it is actually really hard to give you a full debug because every tweak to the script requires a CI build, which can queue for multiple hours...