Simpler way to reproduce this (on linux):

$ rm unicodetest.pyc 
$ 
$ python -c 'import unicodetest'
Result: False
Len: 2 1
Repr: u'\ud800\udd23' u'\U00010123'
$ 
$ python -c 'import unicodetest'
Result: True
Len: 1 1
Repr: u'\U00010123' u'\U00010123'

Storing surrogates in UTF-32 is ill-formed[1], so the first part
definitely shouldn't be failing on linux (with a UTF-32 build).

The repr could go either way, as unicode doesn't cover escape sequences.
 We could allow u'\ud800\udd23' literals to magically become
u'\U00010123' on UTF-32 builds.  We already allow repr(u'\ud800\udd23')
to magically become "u'\U00010123'" on UTF-16 builds (which is why the
repr test always passes there, rather than always failing).

The bigger problem is how much we prohibit ill-formed character
sequences.  We already prevent values above U+10FFFF, but not
inappropriate surrogates.


[1] Search for D90 in http://www.unicode.org/versions/Unicode5.0.0/ch03.pdf