Python python fractions module: round() error?

[Bill Evans at Mariposa]

import fractions round(fractions.Fraction("3.5"))
yields 4, of course. But
round(fractions.Fraction("49886.5"))
yields 49886, not 49887. Why is that?

 

[Bill Evans at Mariposa]

Duh. Never mind. The documentation plainly says it rounds to even.