Preparing v6.2

Hi, these are the changes I found required to make v6.2 build so far. I've not yet gone into functional testing, if I find more I'll attach it here or open new MRs as needed.

I'd be happy if you could check that soon, at least for the changes to the DFSG handling and the tarball - there is quite some pain if the debian/ubuntu tarball mismatch. So if you are ok a timely upload to experimental (to allow me to use the very same tarball in Ubuntu then) would be great.

P.S. please feel free to replace the last commit with a merge that you can directly do, but merge in merge can cause more trouble so I left it to be a simple commit that you can skip as needed.