bookmarks: use 'applychanges' for bookmark update
There is still some use of 'deletedivergent' bookmark here. They will be taken
care of later. The 'deletedivergent' code needs some rework before fitting in
the new world.
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24
$ cd ..