Temporary workaround for python failure on OS X

[fdopen]

This commit should be reverted once the problem is fixed upstream.

See e.g:
https://travis-ci.org/ygrek/ocurl/jobs/364068569#L597
https://travis-ci.org/ocamllabs/ocaml-ctypes/jobs/364740180#L2799
https://travis-ci.org/ocsigen/lwt/jobs/364332682#L125

[yomimono]

Is there an upstream issue number or PR to which we could refer in a comment here? Otherwise the "temporary" workaround is likely to stay forever.

[fdopen]

There is indeed an upstream issue. Let's see, if they reopen it or if the problem will go away soon enough ...
Homebrew/homebrew-core#26358

[yomimono]

I wonder about the wisdom of brew upgrade &> /dev/null || true -- I lack an OSX machine to test on and have no personal experience with brew so I'm happy to defer to another maintainer (perhaps @samoht might have an opinion?), but that seems prone to swallowing important error messages and potentially putting the test system in an inconsistent state.

[samoht]

The breakage seems to be introduced by Homebrew/homebrew-core@57bf428 which was a fix for Homebrew/homebrew-core#26287

The history on that file is quite funny as:

depends_on "python" if MacOS.version <= :snow_leopard

got transformed into:

depends_on "python@2"

which seems a bit extreme... Most of it was due to Homebrew/homebrew-core#24714 which didn't give any explanation on why it was done :-/

[samoht]

Thanks for the workaround!

[ilovezfs]

@samoht the relevant links for the removal of the if MacOS.version <= :snow_leopard are
Homebrew/homebrew-core#26287
Homebrew/homebrew-core#26289

[ilovezfs]

I don't think you'll need the workaround if you use the xcode9.3 Travis image, which I think was created after the python formula became Python 3. See https://docs.travis-ci.com/user/reference/osx/