tests/test-paths

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.

#!/bin/sh
hg init a
hg clone a b
cd a
echo '[paths]' >> .hg/hgrc
echo 'dupe = ../b' >> .hg/hgrc
hg in dupe | fgrep '../'
cd ..
hg -R a in dupe | fgrep '../'
true