Actually, push! behaves strange even with Set{Int64}(), e.g.,
julia> s=Set{Int}()
Set{Int64}()julia> push!(s, 1)
julia> push!(s, 2)
julia> push!(s, 3)
julia> push!(s, 4)
julia> push!(s, 5)
julia> push!(s, 6)
Set([4,2,3,5,6,1])
as compared to doing the same on a v = Int64[], which leads to the expected:
6-element Array{Int64,1}:
1
2
3
4
5
6
