rdepends for apt-cache fails for virtual packages

[Quanah]

Example of problem:

The zimbra-mta package provides mail-transport-agent.

Packages that depend on mail-transport-agent are installed (mailutils,logwatch).

apt-cache is unable to list either of those as depending on zimbra-mta:

root@zre-ldap004:/home/build# apt-cache rdepends --installed mail-transport-agent
<mail-transport-agent>

aptitude does a little better:

root@zre-ldap004:/home/build# aptitude why zimbra-mta
iB mailutils Depends default-mta | mail-transport-agent
ip zimbra-mta Provides mail-transport-agent

so it finds mailutils (but not logwatch). so 50% better than apt-cache

If we try to remove zimbra-mta, we find:

root@zre-ldap004:/home/build# dpkg --purge zimbra-mta
dpkg: dependency problems prevent removal of zimbra-mta:
 mailutils depends on default-mta | mail-transport-agent; however:
  Package default-mta is not installed.
  Package mail-transport-agent is not installed.
  Package zimbra-mta which provides mail-transport-agent is to be removed.
 logwatch depends on postfix | mail-transport-agent; however:
  Package postfix is not installed.
  Package mail-transport-agent is not installed.
  Package zimbra-mta which provides mail-transport-agent is to be removed.

apt-cache kind of functions with postfix as the rdepends:

root@zre-ldap004:/home/build# apt-cache rdepends --installed postfix
postfix
Reverse Depends:
 |logwatch
  libsasl2-2
 |cron

so we pick up logwatch in that case.

However, we *still* fail to find mailutils:

root@zre-ldap004:/home/build# apt-cache rdepends --installed default-mta
<default-mta>

So the rdepends flag for apt-cache seems to be completely broken for virtual packages.

root@zre-ldap004:/home/build# apt-cache showpkg zimbra-mta
Package: zimbra-mta
Versions:
8.7.0.GA.1655.UBUNTU14.64 (/var/lib/dpkg/status)
 Description Language:
                 File: /var/lib/dpkg/status
                  MD5: b25f6328eb0ffec1cb7bcd41cb0ddc9b

Reverse Depends:
Dependencies:
8.7.0.GA.1655.UBUNTU14.64 - zimbra-core (0 (null)) zimbra-mta-components (0 (null)) mail-transport-agent (0 (null)) mail-transport-agent:i386 (0 (null)) mail-transport-agent (0 (null)) mail-transport-agent:i386 (0 (null))
Provides:
8.7.0.GA.1655.UBUNTU14.64 - mail-transport-agent
Reverse Provides:

root@zre-ldap004:/home/build# apt-cache showpkg logwatch
Package: logwatch
Versions:
7.4.0+svn20130529rev144-1ubuntu1 (/var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_trusty_main_binary-amd64_Packages) (/var/lib/dpkg/status)
 Description Language:
                 File: /var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_trusty_main_binary-amd64_Packages
                  MD5: ece539a8a87c5f861d7f0b865e42a03c
 Description Language: en
                 File: /var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_trusty_main_i18n_Translation-en
                  MD5: ece539a8a87c5f861d7f0b865e42a03c

Reverse Depends:
Dependencies:
7.4.0+svn20130529rev144-1ubuntu1 - perl (0 (null)) postfix (16 (null)) mail-transport-agent (0 (null)) fortune-mod (0 (null)) libdate-manip-perl (0 (null))
Provides:
7.4.0+svn20130529rev144-1ubuntu1 -
Reverse Provides:

root@zre-ldap004:/home/build# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.4 LTS"

root@zre-ldap004:/home/build# apt-cache policy apt
apt:
  Installed: 1.0.1ubuntu2.14
  Candidate: 1.0.1ubuntu2.14
  Version table:
 *** 1.0.1ubuntu2.14 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1.0.1ubuntu2.13 0
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
     1.0.1ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jeremy Bícha (jbicha)]

Try this command:

apt-cache showpkg mail-transport-agent