haypo> ord() of Python3 (narrow build) rejects surrogate characters:
haypo> '\U00010000'
haypo> >>> len(chr(0x10000))
haypo> 2
haypo> >>> ord(0x10000)
haypo> TypeError: ord() expected string of length 1, but int found

ord() works fine on Py3, you probably meant to do 
>>> ord('\U00010000')
65536
or
>>> ord(chr(0x10000))
65536

In Py3 is also stated that it accepts surrogate pairs (help(ord)).
Py2 instead doesn't support them:
>>> ord(u'\U00010000')
TypeError: ord() expected a character, but string of length 2 found