dirstate.status: if a file is marked as copied, consider it modified
After a "hg copy --force --after somefile cleanfile", cleanfile
shouldn't be considered clean anymore.
#!/bin/sh
hg init
touch a
hg add a
hg ci -m "a" -d "1000000 0"
echo 123 > b
hg add b
hg diff --nodates
hg diff --nodates -r tip
echo foo > a
hg diff --nodates
hg diff -r ""
hg diff -r tip -r ""
true