David Bremner informs me that shoving everything from the notmuch "git
log" into the debian/changelog is a bit excessive. Instead, we'll
start manually updating this file, (which feels a bit redundant with
NEWS, but perhaps makes us a better Debian-comunity member).
On Bdale Garbee's recommendation I'm switching from gitpkg, (which
constructed a source tree but still required me to go run debuild), to
git-buildpackage. I hadn't originally used git-buildpackage because it
didn't seem to work without a configuration file, (where gitpkg was
fine).
Bdale was kind enough to point me to his fw/altos source at
git.gag.com where I found an example gpb.conf file as well as a target
in debian/rules to automatically update debian/changelog with the new
version number.