Allow callers to pass in the dirstate lock in most localrepo.py funcs. This makes it possible to take the lock once and commit a large number of patches, without having to read and write the dirstate for each patch.

#!/bin/sh
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "0 0"
ls
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "0 0"
hg co 0
# B should disappear
ls