the tensor product below should probably have degree length 2:

    i3 : R = QQ[x][y]

    o3 = R

    o3 : PolynomialRing

    i4 : degreeLength R

    o4 = 2

    i6 : degreeLength tensor(R,R,Join=>false)

    o6 = 1                                   <================== ?
