Preserve apt automatic upgrade Release fields

[hstct]

Preserving NotAutomatic and ButAutomaticUpgrades fields. These fields are used by official Debian backport repositories to indicate to APT that backports should use a default priority.

[quba42]

See the comments below. I am not sure if we should implement the suggestions. Let's discuss it and then upgrade the threads accordingly.

[quba42]

With the exception of the typo in the changelog message, this all looks good to me.

Tested against Debian bookworm-backports and experimental, as well as a repo that does not sport either flag. => Everything works as expected.

[quba42]

Note: Here are some real world test cases illustrating this feature:

alias pulp='pulp -p oci-env'
pulp status

NAME='quickstart-nginx-bookworm-amd64'
REMOTE_OPTIONS=(
  --url=http://nginx.org/packages/debian/
  --distribution=bookworm
  --component=nginx
  --architecture=amd64
  --policy=on_demand
)

NAME='debian-experimental-contrib-amd64'
REMOTE_OPTIONS=(
  --url=http://ftp.de.debian.org/debian/
  --distribution=experimental
  --component=contrib
  --architecture=amd64
  --policy=on_demand
)


NAME='debian-bookworm-backports-contrib-amd64'
REMOTE_OPTIONS=(
  --url=http://ftp.de.debian.org/debian/
  --distribution=bookworm-backports
  --component=contrib
  --architecture=amd64
  --policy=on_demand
)

# For each of the above cases use the following workflow, and then check the published Release file.
pulp deb remote create --name=${NAME} ${REMOTE_OPTIONS[@]}
pulp deb repository create --name=${NAME} --remote=${NAME}
pulp deb repository sync --name=${NAME}
pulp deb publication create --repository=${NAME}
pulp deb distribution create --name=${NAME} --base-path=${NAME} --repository=${NAME}