Names an uninstalled pkg as the reason why a pkg removal fails

[Egmont Koblinger]

I decided to do a bit of cleanup (purge some unused packages) and I ran into this trouble with "apt-get purge":

------------------------------------------------
egmont$ sudo apt-get purge lib32gcc1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nvidia-304 : Depends: lib32gcc1 but it is not going to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
------------------------------------------------
egmont$ sudo apt-get purge nvidia-304
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'nvidia-304' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
------------------------------------------------

So... It can't purge lib32gcc1 because nvidia-304 depends on lib32gcc1, although nvidia-304 is not installed?!? Doesn't make any sense to me. "dpkg -l | grep nvidia-304" -> no match.

On the other hand, "dpkg --purge" correctly tells me that the problem is with nvidia-340-updates's dependencies:

------------------------------------------------
egmont$ sudo dpkg --purge lib32gcc1
dpkg: dependency problems prevent removal of lib32gcc1:
 nvidia-340-updates depends on lib32gcc1.

dpkg: error processing package lib32gcc1 (--purge):
 dependency problems - not removing
Errors were encountered while processing:
 lib32gcc1
------------------------------------------------

So eventually "apt-get purge" is correct that the package can't be removed without breaking dependencies, but it incorrectly names an uninstalled package as the reason rather than an installed one.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: apt 1.0.9.7ubuntu3
ProcVersionSignature: Ubuntu 3.19.0-10.10-generic 3.19.2
Uname: Linux 3.19.0-10-generic x86_64
ApportVersion: 2.16.2-0ubuntu4
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Mar 26 12:37:30 2015
InstallationDate: Installed on 2012-05-30 (1029 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
SourcePackage: apt
UpgradeStatus: Upgraded to vivid on 2015-03-17 (8 days ago)