The Travis scripts checking IOS XE content are ignoring substantial errors

[einarnn]

Taking a look at the Travis error logs, from here:

https://travis-ci.org/github/YangModels/yang/jobs/665635198#L675

...and we can see that there are a large number of reported errors, but the checks are passing. This seems to indicate that there is some broken error checking in the scripts, or perhaps bugs in the tools used to check the YANG modules.

This should be investigated by Cisco.