Log Message:
py-cython: updated to 0.28.3

0.28.3:
Bugs fixed
* Set iteration was broken in non-CPython since 0.28.
* UnicodeEncodeError in Py2 when %s formatting is optimised for unicode strings.
* Work around a crash bug in g++ 4.4.x by disabling the size reduction setting \ 
of the module init function in this version.