Princess & Dragon with Traders & Builders
Yes,

The dragon eliminates followers, builders and pigs according to the Carcassonne annotated FAQ p37.


  Whenever the
  dragon enters a tile occupied by game figures (followers, builders or pigs), they are all returned to
  the relevant player


The rules on what happens to a builder or pig when the last follower is removed from a feature have changed since the initial release of the rules.  The Carcassonne Big Box contains this rule.


  When a player’s last thief, knight, or farmer is removed from a road or city with a
  builder, or field with a pig, the player takes take his builder or pig, putting it in his supply


Just noticed that the Carcassonne Big Box 3 is available.  I checked and the rules are the same in there for this situation.