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R=vadimsh@chromium.org
BUG=swarming:189

Review URL: https://codereview.appspot.com/197250043

pombreda/swarming,pombreda/swarming,luci/luci-py,madecoste/swarming,luci/luci-py,madecoste/swarming,madecoste/swarming,pombreda/swarming,madecoste/swarming,luci/luci-py,luci/luci-py,pombreda/swarming