Automatic merge from submit-queue
only log stacks on server errors
Stack traces on http logging statements can be useful, but you usually only need them for server errors not for things like redirects or even client errors since the server won't be fixing those.
This tightens the "log stack" behavior to only happen for server errors. Messages will still be logged, but the automatic stacks will only come out for server errors.
@enj @mfojtik @smarterclayton
@kubernetes/sig-api-machinery-misc