setup: use changessincelatesttag from archive if present
changessincelatesttag gives one a better idea of how much the code has changed
since. Since changessincelatesttag is always greater than or equal to the
latesttagdistance (see previous patch for why), this will always produce
version numbers greater than or equal to the previous scheme.
basic test for hg debugrebuildstate
$ hg init repo
$ cd repo
$ touch foo bar
$ hg ci -Am 'add foo bar'
adding bar
adding foo
$ touch baz
$ hg add baz
$ hg rm bar
$ hg debugrebuildstate
state dump after
$ hg debugstate --nodates | sort
n 644 -1 bar
n 644 -1 foo
status
$ hg st -A
! bar
? baz
C foo
$ cd ..