Git and packaging: common pattern to keep packaging-files out of the way?

For the last python project I developed, I used git as versioning system. Now it's that time of the development cycle in which I should begin to ship out packages to the beta testers (in my case they would be .deb packages).

In order to build my packages I need a number of extra files (copyright, icon.xpm. setup.py, setup.cfg, stdeb.cfg, etc...) but I would like to keep them separate from the source of the program, as the source might be used to prepare packages for other platforms, and it would make no sense having those debian-specific files lingering around.

My question: is there a standard way/best practice to do so? In my google wanderings I stumbled a couple of times (including here on SO) on the git-buildpackage suite, but I am not sure this is what I am looking for, as it seems that is thought for packagers that download a tar.gz from an upstream repository.

I thought a possible way to achive what I want would be to have a branch on the git repository where I keep my packaging-files, but this branch should also be able to "see" the files on the master branch without me having every time to manually merge the master into the packaging branch. However:

I don't know if this is a good idea / the way it should be done
Although I suspect it might involve some git symbolic-ref magic, I have no idea how to do what I imagined

Any help appreciated, thanks in advance for your time!

Solution

At the end I settled for a branch with a makefile in it, so that my packaging procedure now looks something like:

git checkout debian-packaging
make get-source
make deb
<copy-my-package-out-of-the-way-here>
make reset

If you are interested you can find the full makefile here (disclaimer: that is my first makefile ever, so it's quite possible it's not the best makefile you will ever see).

In a nutshell, the core of the "trick" is in the get-source directive, and it is the use of the git archive command, that accepts the name of a branch as an argument and produces a tarball with the source from that branch. Here's the snippet:

# Fetch the source code from desired branch
get-source:
    git archive $(SOURCE_BRANCH) -o $(SOURCE_BRANCH).tar
    tar xf $(SOURCE_BRANCH).tar
    rm $(SOURCE_BRANCH).tar
    @echo "The source code has been fetched."

Hope this helps somebody else too!