#995004 support updating existing lists in changelog

#995004#5
Date:
2021-09-24 15:53:19 UTC
From:
To:
When adding items to changelog with subitems, we should provide a way to easily deduplicate. E.g.:

* Remove constraints unnecessary since buster:
 + Build-Conflicts: Drop constraint on ant.
 + Build-Conflicts: Drop constraint on blah.

rather than:

* Remove constraints unnecessary since buster:
 + Build-Conflicts: Drop constraint on ant.
* Remove constraints unnecessary since buster:
 + Build-Conflicts: Drop constraint on blah.