Package: dpkg
Version: 1.19.4
man dpkg says:
--forget-old-unavail
Now obsolete and a no-op as dpkg will automatically forget
uninstalled unavailable packages (since dpkg 1.15.4), but
only those that do not contain user information such as
package selections.
Alas, it is not forgetting these uninstalled unavailable packages:
$ grep -B 1 -A 5 'unknown ok not-installed' /var/lib/dpkg/status
Package: libavcodeccvs
Status: unknown ok not-installed
Priority: optional
Section: libs
Bugs: mailto:maril...@debian.org
Architecture: i386
--
Package: libavutilcvs0
Status: unknown ok not-installed
Priority: optional
Section: libs
Bugs: mailto:maril...@debian.org
Architecture: i386
--
Package: modutils
Status: unknown ok not-installed
Priority: extra
Section: admin
Origin: debian
Bugs: debbugs://bugs.debian.org/
Indeed the latter was the cause of #685439.
Perhaps the "unknown" selection state was forgotten about, as on the man
page (#922407).
