newbytes.join doesn't work with generators

[posita]

Python 3.4:

>>> from __future__ import print_function, unicode_literals ; from builtins import *
>>> bytes
<class 'bytes'>
>>> bytes(b''.join(( bytes([ i ]) for i in range(10) ))) # join inside constructor works
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t'
>>> bytes(b'').join(( bytes([ i ]) for i in range(10) )) # join outside constructor works
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t'

Python 2.7:

>>> from __future__ import print_function, unicode_literals ; from builtins import *
>>> bytes
<class 'future.types.newbytes.newbytes'>
>>> bytes(b''.join(( bytes([ i ]) for i in range(10) ))) # join inside constructor works
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t'
>>> bytes(b'').join(( bytes([ i ]) for i in range(10) )) # join outside constructor doesn't work
b''