The diff command appears to be broken in 2.1.0.  I first noticed this when I
tried darcs diff -u --last=1 to get a unified diff of the last recorded patch
and it instead printed ALL the patches.  Here's a simpler example:
 mkdir a
 cd a
 darcs init
 touch a
 darcs add a
 darcs record -a -m "import"
 ls > a
 darcs whatsnew
 darcs diff
We see that the whatsnew clearly shows a change, while the diff is blank (at
least for me).

Duplicate of 1139 (submitted twice)