"apt-get dist-upgrade" shows kept back packages

[Martin T <m4rtntns@gmail.com>]

Hi,

as far as I know, kept back packages in Debian are shown in case
package can not be upgraded with "apt-get upgrade" because upgrade
requires to install new packages. Usually this can be fixed with
apt-get dist-upgrade because this will install new packages if needed.

Now for some reason "db5.1-util" package is kept back despite the fact
that I execute "apt-get dist-upgrade":

root@server:~# apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
  db5.1-util
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
root@server:~#


I even don't need the "db5.1-util" package because it satisfies
dependencies for packages("partimage-server" and "db-upgrade-util")
which I don't have installed:

root@server:~# apt-cache rdepends db5.1-util
db5.1-util
Reverse Depends:
  partimage-server
  db-upgrade-util
root@server:~# apt-cache policy db5.1-util partimage-server db-upgrade-util
db5.1-util:
  Installed: 5.1.29-5
  Candidate: 5.1.29-9
  Version table:
     5.1.29-9 0
        500 http://ftp.debian.org/debian/ stable/main i386 Packages
 *** 5.1.29-5 0
        100 /var/lib/dpkg/status
partimage-server:
  Installed: (none)
  Candidate: 0.6.8-3
  Version table:
     0.6.8-3 0
        500 http://ftp.debian.org/debian/ stable/main i386 Packages
db-upgrade-util:
  Installed: (none)
  Candidate: 5.3.0
  Version table:
     5.3.0 0
        500 http://ftp.debian.org/debian/ stable/main i386 Packages
root@server:~#


Am I correct that "db5.1-util" is kept back because it replaces
libdb5.1 which is required by python2.6 which I have installed? Output
of apt-cache can be seen below:

root@server:~# apt-cache depends db5.1-util
db5.1-util
  Depends: libc6
  Breaks: libdb5.1
  Replaces: libdb5.1
root@server:~# apt-cache rdepends libdb5.1
libdb5.1
Reverse Depends:
  python2.6
  db5.1-util
  db5.1-util
  db5.1-util
root@server:~# apt-cache policy python2.6
python2.6:
  Installed: 2.6.8-1.1
  Candidate: 2.6.8-1.1
  Version table:
 *** 2.6.8-1.1 0
        100 /var/lib/dpkg/status
root@server:~#


thanks,
Martin