Bug#559194: Unused automatically installed packages don't get removed on upgrade

[Uwe Storbeck <uwe@ibr.ch>]

reassign 559194 aptitude,apt
thanks

Same problem occurs when you upgrade a stable system (like from
lenny to squeeze). Some packages don't get removed although they
are marked as automatically installed and no other package depends
on them. I also guess those packages don't get removed by any
package tool because they are set to priority "required".
It affects apt, aptitude and other package tools like deborphan.

If you don't want to remove packages with priority "required"
directly because of stability reasons than maybe resolve the
problem by policy:
To remove a required package always add a transitional package
with reduced priority so that package tools can remove the package
with standard mechanisms.

Regards

Uwe


Package libcap1 as an example:

# aptitude search libcap1
i A libcap1                         - support for getting/setting POSIX.1e capab
==> the package is installed and marked as automatically installed

# aptitude why libcap1
Unable to find a reason to install libcap1.
==> no other package depends on it, recommends or suggests it

# aptitude search '~o'|grep libcap1
i A libcap1                         - support for getting/setting POSIX.1e capab
# apt-cache policy libcap1
libcap1:
  Installed: 1:1.10-14
  Candidate: 1:1.10-14
  Version table:
 *** 1:1.10-14 0
        100 /var/lib/dpkg/status
==> the package is obsolete and not in the debian repository anymore

# aptitude upgrade
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 0 B will be used.
Do you want to continue? [Y/n/?] 
==> but it still doesn't get removed

# apt-get autoremove
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
==> apt also ignores it

# deborphan --guess-all
==> even deborphan does not recognise it

# dpkg -s libcap1
Package: libcap1
Status: install ok installed
Priority: required
Section: libs
[..]
==> package priority is "required",
    probably the reason for the special handling