Run "go mod vendor" in verify-gomod

[rifelpet]

This will actually catch vendoring issues.

also removing it from make travis-ci because make gomod depends on bazel which isnt available in travis. make gomod has its own prow job though, so we still get sufficient coverage.

[k8s-ci-robot]

Skipping CI for Draft Pull Request.
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[k8s-ci-robot]

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[rifelpet]

/test pull-kops-verify-gomod

[justinsb]

Whoops! Thanks for catching this mistake I made :-)

I know it's WIP, but looks good so far!

[rifelpet]

It looks like go is still downloading the modules into the mod cache rather than using the vendor directory. I'm sure theres an env var that we can set in the Makefile to tell go to use the vendor directory every time, and that this default behavior changed between 1.13 and 1.14. k/k is still on 1.13 but is hoping to upgrade to 1.14 for k8s 1.19, so maybe we just follow suit once that lands and our jobs should start using the vendor directory automatically.

regardless, that can be in a followup PR

[rifelpet]

/test pull-kops-verify-gomod

[hakman]

/lgtm

[justinsb]

Thanks @rifelpet . I believe the flag is mod=vendor, and it can be passed to each go invocation or simply set with export GOFLAGS=-mod=vendor.