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
echo 'raise Exception("bit bucket overflow")' > badext.py
abspath=`pwd`/badext.py
echo '[extensions]' >> $HGRCPATH
echo "gpg =" >> $HGRCPATH
echo "hgext.gpg =" >> $HGRCPATH
echo "badext = $abspath" >> $HGRCPATH
hg -q help help