flakey test: downsiding HLL to 4 bits

[johnynek]

[info] ! HyperLogLog.Downsize dense HLLs from 14 bits to 4 bits: Falsified after 0 passed tests.

[info] > Successes: 80 (out of 100)

[info] > Expected successes: 99.72

[info] > Required successes: 84.55

[info] > Example failures:

[info]   >: Exact result: 5000. Approx result: Approximate(566,2575,4585,0.9972).

[info]   >Exact result: 5000. Approx result: Approximate(566,2575,4585,0.9972).

[info]   >Exact result: 5000. Approx result: Approximate(566,2575,4585,0.9972).

[info]   >Exact result: 5000. Approx result: Approximate(566,2575,4585,0.9972).

[info]   >Exact result: 5000. Approx result: Approximate(566,2575,4585,0.9972).

I think what may be happening here is that 4 bits are too small for the std-dev to be a very accurate model, and as such the test is too strict.

[johnynek]

duplicate of #572