Travis passed https://github.com/python/cpython/pull/17366
but a half hour later twice failed
https://github.com/python/cpython/pull/17370

This is build logic's fault, `python3.8` is not guaranteed to be present. I believe Configure is finding pyenv's shim which is present but returns 127 when run if there's no underlying executable to invoke. This is proven by "pyenv: python3.8: command not found".

https://github.com/python/cpython/pull/17371

This looks like Travis' fault, 3.7.1 should be preinstalled in Xenial with `language: c` according to my findings: https://github.com/travis-ci/docs-travis-ci-com/pull/2413/files#diff-fb862f5208fb2361d2280b621831f6b3

I reported this: https://github.com/travis-ci/docs-travis-ci-com/pull/2413#issuecomment-557942367

But note that the text stating that is not yet in the official documentation. (Current text says that it should be preinstalled but not for which languages.)

saying
pyenv: python3.8: command not found
pyenv: version `3.7.1' not installed

-- 
Regards,
Ivan