Mark request as failed even if server replied with error

Existing behavior was able to spam server with badly formated requests.

Change-Id: I10595bae8693a8ca6bb694a6e495da89ae394de9
Reviewed-on: https://weave-review.googlesource.com/1992
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
1 file changed