I'm creating a debian package (.deb) for a system which uses busybox's
dpkg. A deb is an ar-archive (not tar, unix ar) archive, which in turn
contains two tar archives. dpkg will first extract a tar archive called
control.tar.gz (or bz2) from the package, and from that tar it will
extract a file stored with the path "./control". 

The problem is that with the current implementation of tarfile it's
impossible to create a tar archive which would contain a file stored
with the path "./control". This means it's impossible to use tarfile to
create deb packages which would work with busybox' dpkg. 

I'm not 100% sure if that precise path is requirement of the deb file
format, or if it is because of how busybox' dpkg is implemented. However
I have not seen a packaging guide or a deb package which wouldn't have
the control file stored as ./control in the tar archive.