If there is doubt about passing arguments correctly
(as there is in this test), there should be doubt about
getting the results back intact too. Using 0 and 1
(especially 0 for success) makes it easy to get a PASS
accidentally when the return value is not actually
being propagated. Use less common values.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/141110043