Tests broken on Julia 1.3

[YingboMa]

https://travis-ci.org/JuliaDiff/ChainRules.jl/jobs/636506595?utm_medium=notification&utm_source=github_status

I cannot reproduce it locally. @oxinabox do you mind to take a look?

[oxinabox]

They also pass locally for me.

[oxinabox]

I have restarted the job, it could be some weird randomness crept in around the seed
and managed to get it to break on finite differencing.
If so that is an issue, we should have it seeded everywhere

[nickrobinson251]

seem to be passing (and we run CI every night)

[oxinabox]

Have you checked?
If so renenable those tests in Travis CI