Speedup revlog.ancestors for the linear case revlog.ancestors can be expensive on big repos. This cuts down the overall time for hg update by ~19% by short cutting revlog.ancestors when one of the revisions is reachable from another.

#!/bin/sh

hg init a
cd a
echo a > foo
hg add foo
hg commit -m 1 -d "1000000 0"
rm foo
hg remove foo
hg commit -m 2 -d "1000000 0"
hg export 0
hg export 1
hg log -p -r 0
hg log -p -r 1

cd ..
hg clone a b