revset: directly use __contains__ instead of a lambda
We get rid of lambda in a bunch of other place. This is equivalent and much
faster. (no new timing as this is the same change as three other changesets)
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a