Bug#1041836: root unable to write un-owned

[Paul Szabo <paul.szabo@sydney.edu.au>]

Another oddity that should never happen: root cannot write file
that he does not own. Demonstration (root running bash):

  root# touch /tmp/x
  root# ls -l /tmp/x
  -rw-r--r-- 1 root root 0 Aug 10 09:39 /tmp/x
  root# echo a > /tmp/x
  root# chown 2:2 /tmp/x
  root# ls -l /tmp/x
  -rw-r--r-- 1 bin bin 2 Aug 10 09:39 /tmp/x
  root# echo b > /tmp/x
  -bash: /tmp/x: Permission denied
  root# chown 0:0 /tmp/x
  root# ls -l /tmp/x
  -rw-r--r-- 1 root root 2 Aug 10 09:39 /tmp/x
  root# echo c > /tmp/x

This issue seems to reproduce on all machines where I tried.
Quite possibly unrelated (so I may cop some flak) ... or maybe
these "impossible" happenings have a common cause?

Cheers, Paul