localrepo: use dirstate savebackup instead of handling dirstate file manually
This is one step towards having dirstate manage its own storage. It will
be useful for the implementation of sql dirstate [1].
This introduced a small test change: now we always write the dirstate before
saving backup so in some cases where dirstate file didn't exist yet
savebackup can create it.
[1] https://www.mercurial-scm.org/wiki/SQLDirstatePlan
#require no-pure
A script to generate nasty diff worst-case scenarios:
$ cat > s.py <<EOF
> import random
> for x in xrange(100000):
> print
> if random.randint(0, 100) >= 50:
> x += 1
> print hex(x)
> EOF
$ hg init a
$ cd a
Check in a big file:
$ python ../s.py > a
$ hg ci -qAm0
Modify it:
$ python ../s.py > a
Time a check-in, should never take more than 10 seconds user time:
$ hg ci --time -m1
time: real .* secs .user [0-9][.].* sys .* (re)