[x/tour] gotour: fix misleading hint (currently suggests divide by zero)
[x/tour] gotour: fix misleading hint (currently suggests divide by zero)

Fixees issue 15.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/5399051
X-Tour-Commit: 8b076cce91ef5e04070ec9cb987cc458dfa382eb

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website