Polynomials over fraction fields incorrectly converted to Singular

[jakobkroeker]

Currently, we sometimes lose entries in the denominator when converting to Singular:

sage: k.<a> = GF(11^5)
sage: R.<t> = k[]
sage: R.<x> = R.fraction_field()[]
sage: f = x^4 + 1/(a*t)
sage: f._singular_()
x^4
sage: g = x^4 + 1/a * 1/t
sage: f == g
True
sage: g._singular_()
x^4 + (6*a^4 + 5*a)/t

The issue seems to be with elements in the denominator that are subject to a quotient, i.e., an a in the denominator in the above example.