#999851 aptitude: -o does not allow to unset an option

Package:
aptitude
Source:
aptitude
Description:
terminal-based package manager
Submitter:
Dmitry Alexandrov
Date:
2021-11-17 18:03:03 UTC
Severity:
normal
#999851#5
Date:
2021-11-17 17:58:47 UTC
From:
To:
Dear maintainer,

aptitude(8) is unwilling to unset an apt.conf(5) option for a session when instructed to do so with `-o` flag and there does not seem to be any other way to do that.

## Steps to reproduce

	$ aptitude -o APT::Default-Release='' show
	-o requires an argument of the form key=value, got APT::Default-Release=

(judging by a result of any more meaningful command we can conclude that it indeed has not been unset).

## Expected results

aptitude(8) does allow to unset an option temporarily, and uses the above-mentioned syntax for that, since this is what tools from apt package understand already:

	$ apt-cache policy
	Package files:
	 100 /var/lib/dpkg/status
	     release a=now
	 500 https://deb.debian.org/debian rc-buggy/main amd64 Packages
	     release o=Debian,a=experimental,n=experimental,l=Debian,c=main,b=amd64
	     origin deb.debian.org
	 990 https://deb.debian.org/debian sid/main amd64 Packages
	     release o=Debian,a=unstable,n=sid,l=Debian,c=main,b=amd64
	     origin deb.debian.org
	Pinned packages:

	$ apt-cache -o APT::Default-Release='' policy
	Package files:
	 100 /var/lib/dpkg/status
	     release a=now
	 500 https://deb.debian.org/debian rc-buggy/main amd64 Packages
	     release o=Debian,a=experimental,n=experimental,l=Debian,c=main,b=amd64
	     origin deb.debian.org
	 500 https://deb.debian.org/debian sid/main amd64 Packages
	     release o=Debian,a=unstable,n=sid,l=Debian,c=main,b=amd64
	     origin deb.debian.org
	Pinned packages: