`exponent_vectors` of universal polynomials

[SoongNoonien]

Hi, I found some inconsistencies of exponent_vectors:

julia> S=UniversalPolynomialRing(QQ)
Universal Polynomial Ring over Rational Field

julia> i,j=gens(S, ["i","j"])
(i, j)

julia> collect(exponent_vectors(i))
1-element Vector{Vector{Int64}}:
 [1]

julia> collect(exponent_vectors(j))
1-element Vector{Vector{Int64}}:
 [0, 1]

julia> ii=S(i)
i

julia> collect(exponent_vectors(ii))
1-element Vector{Vector{Int64}}:
 [1, 0]

I wondered why they have sometimes different length. First I thought that they may be zero stripped from the right but this is clearly not the case as one can see with ii. As far as I can tell this is caused by the underlying MPolys. By the time i was created S had only one variable, so i.p is contained in a ring with just one variable. But ii is now created from a ring that already has two variables, so the parent of ii.p has two variables (similarly j.p). This can be seen here:

julia> nvars(parent(i.p))
1

julia> nvars(parent(ii.p))
2

julia> nvars(parent(j.p))
2

So, is the current behavior of exponent_vectors intended?