tests/test-rebuildstate.out

diff: add --stat for diffstat output

diff/qdiff --stat invokes patch.diffstat() on the diff output.

When in interactive mode, the output's maximum width is determined by the
terminal's width.

adding bar
adding foo
% state dump after
n 666         -1 bar
n 666         -1 foo
% status
! bar
? baz
C foo