Description of problem:
I just found an very odd behaviour of lastlog on i386 only (I assume this is the only 32bit arch on EL6 available)

# USER=usr$RANDOM; useradd -u 2147483648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr14511         pts/5    freedom.brq.redh Fri May 20 01:22:59 -0400 2011
# USER=usr$RANDOM; useradd -u 2147483648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr166           pts/5    freedom.brq.redh Fri May 20 01:22:59 -0400 2011

As you can see I create a new user with big UID exactly 2^32-1. THis also happens for example for 3147483648, but NOT for 2147483649 or 2147583648, so this is very odd!

# USER=usr$RANDOM; useradd -u 2147583648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr12004                                   **Never logged in**
# USER=usr$RANDOM; useradd -u 2247583648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr5606                                    **Never logged in**
# USER=usr$RANDOM; useradd -u 3247583648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr13946                                   **Never logged in**
# USER=usr$RANDOM; useradd -u 3147483648 $USER; lastlog -u $USER; userdel -r $USER
Username         Port     From             Latest
usr4586          pts/9    localhost        Fri May 20 01:35:13 -0400 2011

Version-Release number of selected component (if applicable):
shadow-utils-4.1.4.2-9.el6

How reproducible:
100%

Steps to Reproduce:
see description  

Actual results:
lastlog shows user logged in 

Expected results:
lastlog shows userd never logged in

Additional info: