bug#10363: /etc/mtab -> /proc/mounts symlink affects df(1) output for /

[jidanni]

The new symlink on Debian,
  $ ls -og /etc/mtab
  lrwxrwxrwx 1 12 12-23 22:00 /etc/mtab -> /proc/mounts
Has caused
  $ df
  Filesystem                                             1K-blocks    Used 
Available Use% Mounted on
  rootfs                                                   1071468  287940    
729100  29% /
  udev                                                      248048       0    
248048   0% /dev
  tmpfs                                                      50564     372     
50192   1% /run
  /dev/disk/by-uuid/551e44e1-2cad-42cf-a716-f2e6caf9dc78   1071468  287940    
729100  29% /
  tmpfs                                                     101128     712    
100416   1% /tmp
  tmpfs                                                     101128       0    
101128   0% /run/shm
  /dev/sda6                                                4270273 3711316    
341987  92% /home
  /dev/sda7                                                5341549 4336289    
733858  86% /var
  /dev/sda8                                                6406856 3024600   
3056800  50% /usr
output to 1) repeat / twice, 2) give the long name for /.
This should be reproducible for anyone who has used standard grub and thus has
  $ grep -h UUID /boot/grub/grub.cfg /proc/cmdline
matches. More details in 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=653073 .