Advise needed for package on github without downloadable tarball

[Andreas Tille <andreas@an3as.eu>]

Hi,

I intended to package

    http://www.kuleuven.be/aidslab/phylogeography/SPREAD.html

which is a phylogeny tool a colleague of mine wanted to use.  I realised
that the source is only available on GitHub and it has no downloadable
tarball.  Is there any recommended procedure to create the pristine source
tarball?  I guess I could clone the repository to our Git and use this
as branch origin/upstream as explained in our policy.  However, I do not
have any idea how to create a reproducible tarball (specifically by also
removing some JARs which are not needed).  I also wonder how to write a
watch file for this.

Any help is welcome

     Andreas.

-- 
http://fam-tille.de