[bump_v18.09] Fix nil pointer dereference in node allocation

[dperny]

Backports #2764 to the newly-named bump_v18.09 branch.

[andrewhsu]

Hmm..I see:

# TODO(stevvooe): Install these from the vendor directory
package github.com/golang/lint/golint: code in directory /home/circleci/.go_workspace/src/github.com/golang/lint/golint expects import "golang.org/x/lint/golint"
make: *** [setup] Error 1
Exited with code 2

[andrewhsu]

@dperny looks like the linter is switched out with PR #2750. may want to cherry-pick from that PR to get these tests passing.