revset-rangeset: call 'getset' on a 'fullreposet'
Calling 'baseset(repo.changelog)' builds a list for all revisions in
the repo. And we already have the lazy and efficient 'fullreposet'
class for this purpose.
This gives us the usual benefit ofs the fullreposet:
revset) 10:100
before) wall 0.002774 comb 0.000000 user 0.000000 sys 0.000000 (best of 797)
after) wall 0.001977 comb 0.000000 user 0.000000 sys 0.000000 (best of 1244)
revset) parents(10):parents(100)
before) wall 0.005054 comb 0.000000 user 0.000000 sys 0.000000 (best of 481)
after) wall 0.002060 comb 0.000000 user 0.000000 sys 0.000000 (best of 1056)