[U-Boot] Travis test/py sandbox_spl test fail

Hi Simon,

I got fail in test/py sandbox_spl, and the log says:

E OSError: [Errno 5] Input/output error

I have no idea about what's wrong in source code, could you help

to take a look?

Travis job:

https://travis-ci.org/keveryang/u-boot/jobs/571125119

Thanks,

- Kever