dirstate: add __contains__ and make __getitem__ more useful
dirstate.state(f) == '?' -> f not in dirstate
dirstate.state(f) -> dirstate[f]
#!/bin/sh
hg init a
cd a
hg init b
echo x > b/x
echo '# should print nothing'
hg st
echo '# should print ? b/x'
hg st b/x
hg add b/x
echo '# should print A b/x'
hg st
echo '# should forget b/x'
hg revert --all
echo '# should print nothing'
hg st b