Trac #25934: Problem displaying a number field (fractional) ideal

With 8.3.rc1:
{{{
sage: K.<a> = NumberField(x^6 - x^5 - 5*x^4 + 4*x^3 + 6*x^2 - 3*x - 1)
sage: K.ideal(1,1)
}}}
takes a long time to return -- why?  Using %time it immediately shows
1ms for the second line but the prompt does not appear until *minutes*
later.  So it is the display of the ideal which is triggering something
long.  In a new session:
{{{
sage: K.<a> = NumberField(x^6 - x^5 - 5*x^4 + 4*x^3 + 6*x^2 - 3*x - 1)
sage: %time I=K.ideal([1,1])
CPU times: user 0 ns, sys: 0 ns, total: 0 ns
Wall time: 1.08 ms
sage: %time I
CPU times: user 0 ns, sys: 0 ns, total: 0 ns
Wall time: 10 µs
<long wait>
}}}

URL: https://trac.sagemath.org/25934
Reported by: cremona
Ticket author(s): John Cremona
Reviewer(s): Frédéric Chapoton, Samuel Lelièvre

src/sage/rings/number_field/number_field.py

@@ -3475,6 +3475,16 @@ def ideal(self, *gens, **kwds):
             Fractional ideal (i + 2)
             sage: K.ideal(0)
             Ideal (0) of Number Field in i with defining polynomial x^2 + 1
+
+        TESTS:
+
+        Check that :trac:`25934` is fixed::
+
+            sage: x = polygen(QQ)
+            sage: K.<a> = NumberField(x^6 - x^5 - 5*x^4 + 4*x^3 + 6*x^2 - 3*x - 1)
+            sage: K.ideal(1,1)
+            Fractional ideal (1)
+
         """
         try:
             return self.fractional_ideal(*gens, **kwds)