dirstate: speed up read and write read: - single call to len(st) - fewer assignments for position tracking - don't split apart tuple from unpack - use a literal for the unpack spec write: - localize variables and functions - avoid copied function call - use % for string concatenation

#!/bin/sh

hg init
touch a
hg add a
hg ci -m "a" -d "1000000 0"

echo 123 > b
hg add b
hg diff --nodates

hg diff --nodates -r tip

echo foo > a
hg diff --nodates

hg diff -r ""
hg diff -r tip -r ""

true