addset: drop caching through generatorset
The utility of this cache is debatable (no visible benchmark impact) and using
generatorset for such purpose makes the code complicated.
We drop it for now. Someone can reintroduce a smart version of it in the future
if it is detected to be relevant.
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present