TestStream_Union is flaky.

[nathanielc]

Need to fix this test since it fails on occasion with:

--- FAIL: TestStream_Union (0.01s)
    streamer_test.go:1796: digraph TestStream_Union {
        stream0 -> stream3;
        stream0 -> stream2;
        stream0 -> stream1;
        stream1 -> union4;
        stream2 -> union4;
        stream3 -> union4;
        union4 -> window5;
        window5 -> map6;
        map6 -> reduce7;
        reduce7 -> http_out8;
        }
    streamer_test.go:1869: unexpected series values: i: 0 
        exp [[1971-01-01 00:00:10 +0000 UTC 24]] 
        got [[1971-01-01 00:00:10 +0000 UTC 23]]

Looks like a data point is being dropped or something.

[nathanielc]

Successful run looks like this:

--- PASS: TestStream_Union (0.10s)
        streamer_test.go:1872: digraph TestStream_Union {
                stream0 -> stream1 [label="63"];
                stream0 -> stream2 [label="63"];
                stream0 -> stream3 [label="63"];
                stream1 -> union4 [label="9"];
                stream2 -> union4 [label="12"];
                stream3 -> union4 [label="9"];
                union4 -> window5 [label="30"];
                window5 -> map6 [label="1"];
                map6 -> reduce7 [label="1"];
                reduce7 -> http_out8 [label="1"];
                }
PASS