Note that this is not breaking the service because the pipeline does not yet depend on these pushes.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/c49b4b304a13b5a8259c2e9bce18c28dafb1b732

commit c49b4b304a13b5a8259c2e9bce18c28dafb1b732
Author: Roberto Carrillo <robertocn@google.com>
Date: Tue Mar 07 23:05:53 2017

Correct wrong key 'user_data' in swarming push endpoint.

It turns out we were assuming the wrong formatting for the message.

R=chanli
BUG= 699259 

Change-Id: I48d935bc0f7790aba2fc70a4521d20777e2ec70e
Reviewed-on: https://chromium-review.googlesource.com/451544
Reviewed-by: Chan Li <chanli@chromium.org>
Commit-Queue: Roberto Carrillo <robertocn@chromium.org>

[modify] https://crrev.com/c49b4b304a13b5a8259c2e9bce18c28dafb1b732/appengine/findit/handlers/swarming_push.py