Casbah 3.0 MongoDBList Strangeness

gistfile1.scala

scala> import com.mongodb.casbah._
import com.mongodb.casbah._

scala> val dbl = MongoDBList()
16:23:48.222 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Registering Scala Conversions.
16:23:48.225 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Deserializers for Scala Conversions registering
16:23:48.226 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Serializers for Scala Conversions registering
16:23:48.227 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Setting up OptionSerializer
16:23:48.232 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Setting up ScalaJCollectionSerializer
16:23:48.238 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Setting up ScalaRegexSerializers
16:23:48.238 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Hooking up scala.util.matching.Regex serializer
16:23:48.239 [Thread-35] DEBUG c.m.c.c.c.s.package$RegisterConversionHelpers$ - Reached base registration method on MongoConversionHelper.
dbl: scala.collection.mutable.Seq[Any] = [ ]

scala> def f(ml:MongoDBList) = {}
f: (ml: com.mongodb.casbah.package.MongoDBList)Unit

scala> f(dbl)
<console>:13: error: type mismatch;
 found   : scala.collection.mutable.Seq[Any]
 required: com.mongodb.casbah.package.MongoDBList
              f(dbl)
                              ^

scala> import com.mongodb.BasicDBList
import com.mongodb.BasicDBList

scala> val dbl2 = new BasicDBList
dbl2: com.mongodb.BasicDBList = [ ]

scala> f(dbl2)    // no error