Failed Travis build

[si14]

Seems like Proper found an error:

https://travis-ci.org/band115/ecirca/jobs/8777848

[si14]

1> {ok, T} =  ecirca:new(4, avg, large)
{ok,{ecirca,#Ref<0.0.0.176>,<<>>,<0.48.0>,large}}
2> ecirca:push_many(T, 4, 66365157401932800).     
ok
3> ecirca:update(T, 3, 36989608025287680).     
{ok,{66365157401932800,51677382713610240}}
4> ecirca:update(T, 3, 397945711586986496).     
{ok,{51677382713610240,167100159004735680}}
5> ecirca:slice(T, 3, 3).     
{ok,[167100159004735680]}

>>> vals = [397945711586986496,36989608025287680,66365157401932800]
>>> avg = sum(vals) / 3
167100159004735658
>>> x = 167100159004735680
>>> avg - x
22

[si14]

Seems like an internal overflow of sum. Not sure what we can do with this.