In cases where the source package comes already with a debian
folder which is located in some subfolder, it can be needed to
specify the path to that file explicitly for git-dch to work
correctly. That's what "$DCH_CHANGELOG_FILE" can be used for.
For example in the Kamailio repository at
https://github.com/kamailio/kamailio you see that there is no
debian folder in the project root. The debian folder is located
under pkg/kamailio/deb/$distribution. When symlinking this folder
to ./debian before starting the build, then git-dch inspects
./debian/changelog but it finds no commit for the latest
changelog entry. So we have to point git-dch to the changelog
file where it is actually committed. By using
this works as intended. Otherwise git-dch will start building a
changelog entry for all commits that exist in the project, but
that will run forever.