The attached patch updates diffoscope to 275.

This version includes some changes to versioned dependencies for various
tests... though guix master may lack some of those version requirements,
so some additional tests may be skipped. Some hope that core-updates
merge will improve test coverage again (e.g. newer "file" if I recall
correctly).

The only dependent package, reprotest, still builds fine, yay!

live well,
  vagrant