Fix compile error.
Fix compile error.

BUG=N/A
R=maruel@chromium.org

Review URL: https://codereview.chromium.org/940963004

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,toddlipcon/luci-go,pombreda/hackspace-client-go,shishkander/luci-go,toddlipcon/luci-go,luci/luci-go,luci/luci-go,pombreda/hackspace-client-go,shishkander/luci-go