Solve fails for `TriangularToeplitz` and `SymmetricToeplitz`

[jishnub]

julia> U = UpperTriangularToeplitz(Float64[1,2,3,4])
4×4 UpperTriangularToeplitz{Float64, Vector{Float64}}:
 1.0  2.0  3.0  4.0
  ⋅   1.0  2.0  3.0
  ⋅    ⋅   1.0  2.0
  ⋅    ⋅    ⋅   1.0

julia> U \ Float64[1,2,3,4]
4-element Vector{Float64}:
 NaN
 NaN
 NaN
 NaN

julia> Matrix(U) \ Float64[1,2,3,4]
4-element Vector{Float64}:
  0.0
  0.0
 -5.0
  4.0

[jishnub]

Similarly,

julia> SymmetricToeplitz(Float64[1,2,3,4]) \ Float64[1,2,3,4]
4-element Vector{Float64}:
 NaN
 NaN
 NaN
 NaN

julia> Matrix(SymmetricToeplitz(Float64[1,2,3,4])) \ Float64[1,2,3,4]
4-element Vector{Float64}:
 1.0
 0.0
 0.0
 0.0