Shapeless Poly woes when combining default case with case over sealed hierarchy (and a solution)

Ammonite Repl session

Welcome to the Ammonite Repl 0.5.2
(Scala 2.11.7 Java 1.8.0_51)
@ load.ivy("com.chuusai" %% "shapeless" % "2.2.5")

@ import shapeless._
import shapeless._
@   sealed trait Country
defined trait Country
@   case object Germany extends Country
defined object Germany
@   case object Australia extends Country
defined object Australia
@ def eg1 = "Einstein" :: 1879 :: Germany :: HNil
defined function eg1
@   object ExamplePoly extends Poly1 {
      implicit def default[T] = at[T](x => x)
      implicit def yearsSinceBirth = at[Int](2016 - _)
      //following http://stackoverflow.com/questions/20894593/subtype-polymorphism-in-shapeless-mapping
      implicit def isAustralian[C <: Country] = at[C](_ == Australia)
    }
defined object ExamplePoly
@ eg1.map(ExamplePoly)
Compilation Failed
Main.scala:272: could not find implicit value for parameter mapper: shapeless.ops.hlist.Mapper[cmd7.ExamplePoly.type,shapeless.::[String,shapeless.::[Int,shapeless.::[cmd3.Germany.type,shapeless.HNil]]]]
eg1.map(ExamplePoly)
       ^

//How I eventually solved it
@ trait IdentityDefault extends Poly1 {
  implicit def default[T] = at[T](x => x)
  }
defined trait IdentityDefault
@ object ExamplePoly3 extends IdentityDefault {
        implicit def yearsSinceBirth = at[Int](2016 - _)
        implicit def isAustralian[C <: Country] = at[C](_ == Australia)
      }
defined object ExamplePoly3
@ eg1.map(ExamplePoly3)
res11: String :: Int :: Boolean :: HNil = ::("Einstein", ::(137, ::(false, HNil)))

Looks like an ambiguous implicit, right?
implicit def default[T] matches everything and for cases where either yearsSinceBirth or isAustralian match as well the compiler doesn't know which to choose.