dirstate: add __contains__ and make __getitem__ more useful
dirstate.state(f) == '?' -> f not in dirstate
dirstate.state(f) -> dirstate[f]
#!/bin/sh
mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status