TestThrottle failed travis

[jrick]

Saw this from Travis-CI on a PR:

=== RUN TestThrottle
--- FAIL: TestThrottle (0.05s)
rpcserver_test.go:54: status codes: want: map[200:1 429:1], got: map[200:2]

Must be an intermittent issue because this is the first time I've seen this fail since the RPC throttling was added.

[jrick]

Looked at the test case and I can see it's a race there and not a bug with the throttle function (when isn't waiting using time.Sleep a race?). In this case, the sleep finished before the second handler started, so both handlers ran and returned HTTP 200 status codes.