6.3.3. Common misconceptions about changelog entries
The changelog entries should not document generic packaging issues (Hey, if you’re looking for foo.conf, it’s in /etc/blah/.), since administrators and users are supposed to be at least remotely acquainted with how such things are generally arranged on Debian systems. Do, however, mention if you change the location of a configuration file.
The only bugs closed with a changelog entry should be those that are actually fixed in the same package revision. Closing unrelated bugs in the changelog is bad practice. See When bugs are closed by new uploads.
The changelog entries should not be used for random discussion with bug reporters (I don’t see segfaults when starting foo with option bar; send in more info), general statements on life, the universe and everything (sorry this upload took me so long, but I caught the flu), or pleas for help (the bug list on this package is huge, please lend me a hand). Such things usually won’t be noticed by their target audience, but may annoy people who wish to read information about actual changes in the package. See Responding to bugs for more information on how to use the bug tracking system.
It is an old tradition to acknowledge bugs fixed in non-maintainer uploads in the first changelog entry of the proper maintainer upload. As we have version tracking now, it is enough to keep the NMUed changelog entries and just mention this fact in your own changelog entry.