There are other unfixed messages (may be introduced after 3.3):

>>> b''.join([''])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: sequence item 0: expected bytes, bytearray, or an object with the buffer interface, str found
>>> str(42, 'utf8')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: coercing to str: need bytes, bytearray or buffer-like object, int found
>>> import array; array.array('B').frombytes(array.array('I'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: string/buffer of bytes required.
>>> import socket; print(socket.socket.sendmsg.__doc__)
sendmsg(buffers[, ancdata[, flags[, address]]]) -> count

Send normal and ancillary data to the socket, gathering the
non-ancillary data from a series of buffers and concatenating it into
a single message.  The buffers argument specifies the non-ancillary
data as an iterable of buffer-compatible objects (e.g. bytes objects).
The ancdata argument specifies the ancillary data (control messages)
as an iterable of zero or more tuples (cmsg_level, cmsg_type,
cmsg_data), where cmsg_level and cmsg_type are integers specifying the
protocol level and protocol-specific type respectively, and cmsg_data
is a buffer-compatible object holding the associated data.  The flags
argument defaults to 0 and has the same meaning as for send().  If
address is supplied and not None, it sets a destination address for
the message.  The return value is the number of bytes of non-ancillary
data sent.

And there are several mentions of "buffer-like" or "buffer-compatible" in the documentation.