Ant conditions - which comes first 'if' or 'unless'

Question

If an ant target uses both if and unless, which is evaluated first?

Example

What comes first, the chicken or the egg? . . .

<target name="prepare" if="chicken" unless="egg" >
    <echo>Dinner time. Chicken is served!</echo>
</target>

Would ant evaluate the chicken property first? Or the egg property?