Use bazelisk instead of specifying bazel version manually.

[ailzhang]

Bazelisk automatically reads .bazelversion file and install the required version of Bazel. This saves us from updating CI script everytime we need a Bazel upgrade.
Use clang-8 for consistency with pytorch/xla repo.

[dr-ci]

💊 CircleCI build failures summary and remediations

As of commit 0cc1802:

• 1/1 failures introduced in this PR

Detailed failure analysis

One may explore the probable reasons each build failed interactively on the Dr. CI website.

🕵️ 1 new failure recognized by patterns

The following build failures do not appear to be due to upstream breakage:

pytorch_linux_xenial_py2_7_9_test (1/1)

Step: "Test" (full log | pattern match details)

Feb 10 22:05:51 RuntimeError: test_nn failed!

Feb 10 22:05:51   File "/opt/python/2.7.9/lib/python2.7/site-packages/xmlrunner/runner.py", line 7, in <module> 
Feb 10 22:05:51     from .result import _XMLTestResult 
Feb 10 22:05:51   File "/opt/python/2.7.9/lib/python2.7/site-packages/xmlrunner/result.py", line 42, in <module> 
Feb 10 22:05:51     for (low, high) in _illegal_unichrs 
Feb 10 22:05:51 ValueError: chr() arg not in range(256) 
Feb 10 22:05:51 Traceback (most recent call last): 
Feb 10 22:05:51   File "test/run_test.py", line 457, in <module> 
Feb 10 22:05:51     main() 
Feb 10 22:05:51   File "test/run_test.py", line 450, in main 
Feb 10 22:05:51     raise RuntimeError(message) 
Feb 10 22:05:51 RuntimeError: test_nn failed! 
Feb 10 22:05:51 + cleanup 
Feb 10 22:05:51 + retcode=1 
Feb 10 22:05:51 + set +x 
Feb 10 22:05:51 =================== sccache compilation log =================== 
Feb 10 22:05:51 =========== If your build fails, please take a look at the log above for possible reasons =========== 
Feb 10 22:05:51 Compile requests                 10 
Feb 10 22:05:51 Compile requests executed         8 
Feb 10 22:05:51 Cache hits                        2 
Feb 10 22:05:51 Cache misses                      6 
Feb 10 22:05:51 Cache timeouts                    0 

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This comment has been revised 9 times.

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@ailzhang has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[mruberry]

Cool!

[facebook-github-bot]

@ailzhang has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[facebook-github-bot]

@ailzhang merged this pull request in a3e69d3.