ARROW-7760: [Release] Fix verify-release-candidate.sh since pip3 seems to no longer be in miniconda, install miniconda unconditionally

[wesm]

This change was necessary for me to get the script to finish to completion.

[github-actions]

Thanks for opening a pull request!

Could you open an issue for this pull request on JIRA?
https://issues.apache.org/jira/browse/ARROW

Then could you also rename pull request title in the following format?

ARROW-${JIRA_ID}: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - How to contribute patches

[pitrou]

If you are sure you're using Python 3, I would say python3 -m pip install ... is the surest way.

[wesm]

This step is invoked from within a conda environment that is set up in the script. I guess recently (January 2020-related?) the pip3 alias disappeared

[kszucs]

The conda environment wouldn't have been installed in certain flag configuration:

TEST_DEFAULT=0 TEST_INTEGRATION_GO=1 dev/release/verify-release-candidate.sh source 0.16.0 2

[kszucs]

Changed the script to always use miniconda.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-7760

[wesm]

+1

[wesm]

I'm just running this locally and then will merge

[wesm]

There's still some problems, working on fixes

[wesm]

There were multiple other problems:

• Current miniconda doesn't place a python or pip into PATH when running conda.sh (like it used to?) I guess this is to discourage people installing stuff in the root environment. So now we set up the "arrow-test" conda environment unconditionally
• Selective disabling of integration test components was broken (so TEST_DEFAULT=0 TEST_SOURCE=1 TEST_INTEGRATION_GO=1 dev/release/verify-release-candidate.sh source 0.16.0 2 from above still failed)
• Added a more helpful error message when you forget to put TEST_SOURCE=1 when using TEST_DEFAULT=0

[wesm]

+1 again, I've put this through the paces locally (had to modify the verification script to install $ARROW_DIR/dev/archery to test the archery changes)