darktable: can't open raw DNG files from film scanner (Epson V600)

It is a patch for rawspeed, and it should fix the problem. The PR author is LibRaw.

I have edited my post above. The libraw tools can read 29.dng. The fault was in my head.

Vuescan works under Linux & .dng from it works well with Darktable (negadoctor). Vuescan doesn’t come from a big companies, it’s a one man work. Free software concerns libraries which can be used by a lot sofwares. Vuescan is an end users software not a library.