dirstate: fix rebuild; add a test
If rebuild calls invalidate, it will just queue a (re)read of the dirstate
file, while what we really want is to empty the current state.
#!/bin/sh
# test command parsing and dispatch
hg init a
cd a
echo a > a
hg ci -Ama -d '0 0'
echo "# missing arg"
hg cat
echo '% [defaults]'
hg cat a
cat > $HGRCPATH <<EOF
[defaults]
cat = -v
EOF
hg cat a
echo '% no repo'
cd ..
hg cat
exit 0