Fix performance regression in addremove command.
When I rewrote addremove, I lazily put a call to repo.changes in,
which was unnecessary and slow. This is a new rewrite, preserving the
file name behaviour, but replacing the call to repo.changes with a walk,
which is much cheaper, and avoids calls to os.stat on all but files that
have probably been deleted.
+ hg clone a b
abort: repository a/.hg not found!
+ echo 255
255
+ hg clone http://127.0.0.1:3121/a b
requesting all changes
abort: error: Connection refused
+ echo 255
255
+ rm -rf b
+ mkdir a
+ chmod 000 a
+ hg clone a b
abort: repository a/.hg not found!
+ echo 255
255
+ mkdir b
+ cd b
+ hg init
+ hg clone . ../a
abort: destination '../a' already exists
+ echo 1
1
+ cd ..
+ chmod 700 a
+ rm -rf a b
+ mkfifo a
+ hg clone a b
abort: repository a/.hg not found!
+ echo 255
255
+ rm a
+ mkdir q
+ cd q
+ hg init
+ cd ..
+ hg clone q
abort: destination 'q' already exists
+ true