revset: use `subset &` in `divergent`
This takes advantage of the `fullreposet` smartness.
revset #0: divergent()
0) wall 0.002047 comb 0.000000 user 0.000000 sys 0.000000 (best of 813)
1) wall 0.000052 comb 0.000000 user 0.000000 sys 0.000000 (best of 22757)
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown