revset: use `subset &` in `filelog`
This takes advantage of the `fullreposet` smartness.
revset #0: file(COPYING)
0) wall 3.179066 comb 3.180000 user 3.140000 sys 0.040000 (best of 3)
1) wall 2.723699 comb 2.730000 user 2.690000 sys 0.040000 (best of 4)
$ 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