Introduce experimental 'never' pinning for sources

This allows disabling a repository by pinning it to 'never',
which is internally translated to a value of -32768 (or whatever
the minimum of short is).

This overrides any other pin for that repository. It can be used
to make sure certain sources are never used; for example, in
unattended-upgrades.

To prevent semantic changes to existing files, we substitute
min + 1 for every pin-priority: <min>. This is a temporary
solution, as we are waiting for an ABI break.

To add pins with that value, the special Pin-Priority
"never" may be used for now. It's unclear if that will
persist, or if the interface will change eventually.

(cherry picked from commit 8bb2a91a070170d7d8e71206d1c66a26809bdbc3)
LP: #1814727
(cherry picked from commit f52e7a2040f461fb37f88751f5a42a5d5c130441)
(cherry picked from commit c55c0ade9ea7f084111884b282c0ffd632ad6c55)

0 files changed, 0 insertions, 0 deletions