Primary decomposition in one variable not working

edit

The following doesn't work, it yields a NotImplementedError:

R.<x> = GF(2)[]
I = R.ideal(x^3+1)
I.primary_decomposition()

However, if I introduce a superfluous variable y, it works:

R.<x,y> = GF(2)[]
I = R.ideal(x^3+1,y)
I.primary_decomposition()

Compare: https://ask.sagemath.org/question/567...

As far as I understood correctly, PolynomialRing(K) is the same as K[], but PolynomialRing(K,1) is different. Let's try it out, it works:

R.<x> = PolynomialRing(GF(2),1)
I = R.ideal(x^3+1)
I.primary_decomposition()