Pylint crash with AttributeError in Travis CI while working fine on local computer

The failed builds are here:
https://travis-ci.com/SLAPaper/Project-KnowNet/builds/102466002

It seems that the pylint installation has some problems in Travis CI environment but I can’t quite figure out why.
Since pylint works fine in local environment and I can’t search any related issue on pylint side, so I reach here for help.

The error message is here:

Did this help you? https://travis-ci.com/SLAPaper/Project-KnowNet/builds/102486785

Yes, I change the travis config, and it magically works, but I don’t quite know why.

Anyway thanks for help!

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