Description of problem:
os.lstat() returns negative values for owner and/or group for users with huge UID/GIDs on i386 arch while on other archs it is positive as expected and on i386 also libuser returns positive values. This is not a regression. 

Version-Release number of selected component (if applicable):
python-2.6.6-20.el6.i686
python-2.6.5-3.el6_0.2.i686

How reproducible:
always

Steps to Reproduce:
1. # adduser -u 4294967293  foo
2. # python
>>> import os
>>> os.lstat('/home/foo/')
3.
  
Actual results:
Negative UID -> st_uid=-3:
>>> os.lstat('/home/foo/')
posix.stat_result(st_mode=16832, st_ino=523265L, st_dev=64770L, st_nlink=4, st_uid=-3, st_gid=506, st_size=4096L, st_atime=1303126993, st_mtime=1303126936, st_ctime=1303126936)

Expected results:
Unchanged UID value ->  st_uid=4294967293:
>>> os.lstat('/home/foo/')
posix.stat_result(st_mode=16832, st_ino=16, st_dev=64771L, st_nlink=2, st_uid=4294967293, st_gid=502, st_size=1024, st_atime=1303126860, st_mtime=1303126860, st_ctime=1303126860)

Additional info:
The issue is causing failures in s-c-users on i386 systems when reproducing bug
https://bugzilla.redhat.com/show_bug.cgi?id=628730 but it might have also other negative implications.