tc_pybind_example.py occasionally fails on tuning cache check

[skimo-openhub]

See, e.g., https://ci.pytorch.org/jenkins/job/tensorcomp-builds/job/tc-cuda9.0-cudnn7.1-ubuntu16.04-devel-build-test/259/consoleText

I was able to reproduce it on my system. top10 contains exactly one element, but it is different from top1. The element in top10 corresponds to the one in the protobuf file.