is_abelian throws

[thofma]

The following should work:

julia> F, a = cyclotomic_field(7,:a)
(Cyclotomic field of order 7, a)

julia> P,x = polynomial_ring(F,:x)
(Univariate polynomial ring in x over F, x)

julia> FG,dd = number_field(x^6 + (133486969//288*a^5 - 223759151//432*a^4 - 223759151//432*a^3 + 133486969//288*a^2 - 232474865//288)*x^3 - 840539241479//13824*a^5 - 18036715089631//9216*a^4 - 18036715089631//9216*a^3 - 840539241479//13824*a^2 - 7320065966297//9216)
(Relative number field of degree 6 over F, _$)

julia> is_abelian(FG)
ERROR: Number field element not in the order
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35

Error is due to "non-nice" defining polynomial.