Looks like a recent regression. 

Ah, this was broken by https://chromium-review.googlesource.com/c/374719/

I think I have a fix for this. We need integration testing!

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra.git/+/77d46889371d80147d9092789d0fc73372bd65c8

commit 77d46889371d80147d9092789d0fc73372bd65c8
Author: Sean McCullough <seanmccullough@chromium.org>
Date: Thu Aug 25 18:52:18 2016

[som] Fix some frontend tests and code broken by the reasons refactoring.

In the future we need to be more careful about making sure that changes
to the JSON format are tested on the client and don't break things there.
The example alerts in test/alerts-data.js should be updated whenever we
make changes to alerts-dispatcher that alter the structure of the json it
produces.

BUG= 640879 

Change-Id: Ie515ad81bcfe7fdc3ab1a48d515fff176be0c0a6
Reviewed-on: https://chromium-review.googlesource.com/376100
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Sean McCullough <seanmccullough@chromium.org>

[modify] https://crrev.com/77d46889371d80147d9092789d0fc73372bd65c8/go/src/infra/appengine/sheriff-o-matic/elements/som-examine.html
[modify] https://crrev.com/77d46889371d80147d9092789d0fc73372bd65c8/go/src/infra/appengine/sheriff-o-matic/elements/som-extension-build-failure.html
[modify] https://crrev.com/77d46889371d80147d9092789d0fc73372bd65c8/go/src/infra/appengine/sheriff-o-matic/test/alerts-data.js
[modify] https://crrev.com/77d46889371d80147d9092789d0fc73372bd65c8/go/src/infra/appengine/sheriff-o-matic/test/som-examine-test.html
[modify] https://crrev.com/77d46889371d80147d9092789d0fc73372bd65c8/go/src/infra/appengine/sheriff-o-matic/test/som-extension-build-failure-test.html