bdiff: switch to lyhash lyhash is a very simple and fast hash function that had the fewest hash collisions on a 3.9M line text corpus and 190k line binary corpus and should have significantly fewer collisions than the current hash function.

#!/bin/sh

hg init dir
cd dir
echo bleh > bar
hg add bar
hg ci -m 'add bar'

hg cp bar foo
echo >> bar
hg ci -m 'cp bar foo; change bar'

hg debugrename foo
hg debugindex .hg/store/data/bar.i