Regression in typealias with Union{}

[nalimilan]

This used to work on 0.4.5:

julia> typealias VecOrNullableVec{T} Union{AbstractVector{T}, AbstractVector{Nullable{T}}}
AbstractArray{T,1}

julia> VecOrNullableVec{Int}
AbstractArray{Int64,1}

julia> AbstractArray{Nullable{Int},1} <: VecOrNullableVec{Int}
false

[JeffBezanson]

Caused by 0ffba40

[JeffBezanson]

closed by #18457