Fix cold cache diff performance cold cache diff performance has regressed in two ways. localrepo.changes has optimizations for diffing against the working dir parent that expect node1 to be None. commands.revpair() usage means that commands.dodiff() never sends node1 == None. This is fixed in localrepo.changes by checking against the dirstate parents. In the non-dirstate parents case, localrepo.changes does a loop comparing files without first sorting the file names, leading to random access across the disk.

#!/bin/sh
#
# Corrupt an hg repo with two pulls.
#

# create one repo with a long history
hg init source1
cd source1
touch foo
hg add foo
for i in 1 2 3 4 5 6 7 8 9 10; do
    echo $i >> foo
    hg ci -m $i
done
cd ..

# create a third repo to pull both other repos into it
hg init version2
hg -R version2 pull source1 &
sleep 1

hg clone --pull -U version2 corrupted
hg -R corrupted verify
hg -R version2 verify