shelve: really pass publicancestors to changegroupsubset - not the parents
publicancestors returned the parents of the public ancestors ... and
changegroupsubset used the parents of these as base for the bundle. That gave
bundles with one layer of changesets more than necessary.
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 ..