Get add and locate to use new repo and dirstate walk code. They use a walk function that abstracts out the irritating details, so that there's a higher likelihood of commands behaving uniformly.

+ hg init
+ echo This is file a1
+ hg add a
+ hg commit -t 'commit #0' -d '0 0' -u user
+ ls
a
+ echo This is file b1
+ hg add b
+ hg commit -t 'commit #1' -d '0 0' -u user
+ hg co 0
+ ls
a