revset: fast implementation for fullreposet.__and__ "And" operation with something that contains the whole repo should be super cheap. Check method docstring for details. This provide massive boost to simple revset that use `subset & xxx` revset #0: p1(20000) 0) wall 0.002447 comb 0.010000 user 0.010000 sys 0.000000 (best of 767) 1) wall 0.000529 comb 0.000000 user 0.000000 sys 0.000000 (best of 3947) revset #1: p2(10000) 0) wall 0.002464 comb 0.000000 user 0.000000 sys 0.000000 (best of 913) 1) wall 0.000530 comb 0.000000 user 0.000000 sys 0.000000 (best of 4226) No other regression spotted. More performance improvements are expected in the future as more revset predicate are converted to use `subset & xxx` The relaxed way `fullreposet` handles "&" operation may cause some trouble for people comparing smartset from different filter levels. I'm not sure such people exist and we can improve that aspect in later patches.