bisect: use array.array rather than lists for ancestor lists
This nearly doubles performance and cuts memory usage in half on large
bisections.
#!/bin/sh
hg init a
cd a
echo 'root' >root
hg add root
hg commit -d '0 0' -u test -m "Adding root node"
echo 'a' >a
hg add a
hg branch a
hg commit -d '1 0' -u test -m "Adding a branch"
hg update -C 0
echo 'b' >b
hg add b
hg branch b
hg commit -d '2 0' -u test -m "Adding b branch"
echo 'bh1' >bh1
hg add bh1
hg commit -d '3 0' -u test -m "Adding b branch head 1"
hg update -C 2
echo 'bh2' >bh2
hg add bh2
hg commit -d '4 0' -u test -m "Adding b branch head 2"
echo 'c' >c
hg add c
hg branch c
hg commit -d '5 0' -u test -m "Adding c branch"
hg branches
echo '-------'
hg branches -a