Scala case classes don't have auxiliary constructors?

The lesson of today, is that Scala case classes don't appear to have auxiliary constructors.

In Scala, auxiliary constructors may be added to a class by defining a "this" method:

scala> class AClass(s1: String, s2: String) {
  def this(s: String) = this(s, "default")
}
defined class AClass

scala> new AClass("hey")
res0: AClass = AClass@187b5ff

Look what happens when you try the same trick on a case class:

scala> case class ACaseClass(s1: String, s2: String) {
  def this(s: String) = this(s, "default")
}
defined class ACaseClass

scala> ACaseClass("hey")
:7: error: wrong number of arguments for method apply: (String,String)ACaseClass in object ACaseClass
ACaseClass("hey")
^

The attempt at adding an auxiliary constructor compiles, but results in a runtime error.

Update: Oops, yes the can have auxiliary constructors --- see comment below, by jkriesten, straightening things out!

Update: Paul (see comment below) points to the following discussion on this topic http://www.scala-lang.org/node/976.