FWIW, the output is a bit different here before the patch:
$ ./python -c "import platform; print(platform.linux_distribution())"
('Mandriva Linux', '2010.1', 'Official')

and after the patch:
$ ./python -c "import platform; print(platform.linux_distribution())"
('MandrivaLinux', '2010.1', 'Henry_Farman')

but I would say it's because Mandriva has inconsistent contents in their respective /etc/mandriva_release and /etc/lsb-release files.

The patch itself is a bit imperfect and will need reworking (_u_distname, _u_version and _u_id should be initialized to '' rather than catching UnboundLocalError; remove ubuntu-specific comments).