TST/CI: PyArrow Test Failures

[gfyoung]

Weird pyarrow failures going on with 37e23d:

https://travis-ci.org/pandas-dev/pandas/jobs/276857797
https://travis-ci.org/pandas-dev/pandas/jobs/276857799

Looks unrelated to commit, so something probably went wrong with pyarrow

cc @jreback @jorisvandenbossche @wesm

[wesm]

Just updated packages to 0.7.0 today, so let's investigate and resolve

[jorisvandenbossche]

Looking at the green build before, there has been a pyarrow update from 0.6.0 to 0.7.0

[wesm]

Yeah, so it looks like a feature that was unsupported before is now supported, so this is a good kind of failure

[wesm]

I recommend that we pin pandas builds at a particular pyarrow version so that we can update pandas and fix bugs in a PR rather than letting builds randomly start failing

[jreback]

most of the builds are pinned

but to catch things like this on purpose i did not pin several

[wesm]

Oh nice. Can we set one of the builds in the build matrix to run against the nightlies (conda install pyarrow -c twosigma) with allowed failures? That might be helpful to get early feedback in case there is a regression or some other failure

[gfyoung]

@jreback : Maybe it would be better to add pyarrow builds like these to allowed failures? No reason to block PR's just because of a 3rd-party library update that is unrelated to their changes.

[gfyoung]

@wesm : Along similar lines to what you said, perhaps we could just run an allowed-failure build of pandas against a nightly build as one of our allowed failures just so we can catch these compat issues in advance.

[jreback]

no its much better to flag this in a highly visible manner - allowed failures are only marked this way to make the build turn 'finish' faster - they r still not allowed

the pr to fix will take about 5 minutes
welcome for someone to do it otherwise i will tomorrow

[jreback]

further his is very common and has happened many times with matplotlib and dateutil among others

[jreback]

we already have a build that hits numpy / scipy dailies. easy enough to add pyarrow

[gfyoung]

they r still not allowed

True, it's just that I think people freak out more when they see a failure on the non-allowed failures.