The distribution name returned by platform.dist() depends on the order
of os.path.listdir( '/etc' ). It selects the first file matching the
regex r'(\w+)[-_](release|version)' and takes part of the file name
(i.e. matchResult.groups()[0]) as distribution name. But there are often
several files matching this pattern (at least on Fedora and Mandriva).
For instance, on a Mandriva 2007.1 official, I can see the following files:

[login@localhost ~]$ ls -l /etc/*-release
-rw-r--r-- 1 root root 137 jan 18  2007 /etc/lsb-release
lrwxrwxrwx 1 root root  16 oct  7 17:32 /etc/mandrakelinux-release ->
mandriva-r                                                             
                              elease
lrwxrwxrwx 1 root root  16 oct  7 17:32 /etc/mandrake-release ->
mandriva-releas                                                        
                                   e
-rw-r--r-- 1 root root  50 avr  2  2007 /etc/mandriva-release
lrwxrwxrwx 1 root root  16 oct  7 17:32 /etc/redhat-release ->
mandriva-release

Therefore, the result for platform.distrib()[0] could be mandriva,
mandrake, redhat or even lsb. The first match wins !

Ignoring symlinks could remove part of the problem. On Mandriva, it
would leave only lsb-release and mandriva-release. It is possible to
select the good one by ignoring lsb-release or by verifying the file's
content (mandriva-release has one line and lsb-release has several
lines). I do not know if the second method is portable.