Annoying behavior when dropping directorty in dired buffer

[Mathias Dahl]

Would it be possible to configure what should happen when I drop a
directory into a dired buffer? The current behavior is extremely
annoying. I get this error:

  Recursive copies not enabled.\nSee variable dired-recursive-copies.

I could change that variable but I do not want anything else than the
directiry opening in yet another dired buffer. I don't want to drag
and drop directories to get them moved/copied/linked.