Under what circumstances does the rename fail after the hard link succeeds?

What is the reasoning for using O_NOLINKS when reading krb5.conf?  (If you 
can determine the reasoning; I realize that it might be an old change.)

It seems that even with the proposed change, there will always be a short 
window where an open with O_NOLINKS will fail while a profile file is being 
updated.  So there will still be a reliability issue associated with using 
O_NOLINKS.  To remove that issue, we would have to eliminate the backup 
file or create it using a copy operation.