• shared references were not decoded correctly: instead of getting
  multiple references to the same object, you got the same
  reference to the same object, causing a number of issues. For
  example, modifying the reference would modify all places the
  reference was used, and encoding the decoded structure would
  unshare the previously shared hashes, as trheir reference count
  would be 1. Fixing this was rather involved, as perl lacks the
  ability to easily swap or copy arrays and hashes.