Any news on this?

Just as a note, pickletools.py also does not reflect the current behaviour; pickle types STRING, BINSTRING and SHORT_BINSTRING are all defined with stack_after=[pystring]:

[1, line 992]
    I(name='STRING',
      code='S',
      arg=stringnl,
      stack_before=[],
      stack_after=[pystring],
      proto=0,
      doc=(...)
     )

although the doc=... does describe it will be decoded, the object type of pystring is still defined as bytes:

[1, line 747]
pystring = StackObject(
               name='string',
               obtype=bytes,
               doc="A Python (8-bit) string object.")


[1] http://hg.python.org/cpython/file/98df29d51e12/Lib/pickletools.py