rust: less set lookups in MissingAncestors using the return values of HashSet::remove(), we can factor pairs of `contains()/remove()` into a single `remove()`. On a perfdiscovery run done on the PyPy repository, prepared with contrib/discovery-helper.sh 50 100, I do get a modest improvement with this (mean of medians of three runs is better by 2%) Sample readings, before this change: ! wall 0.175609 comb 0.180000 user 0.180000 sys 0.000000 (median of 58) With this change: ! wall 0.171662 comb 0.180000 user 0.170000 sys 0.010000 (median of 60) Differential Revision: https://phab.mercurial-scm.org/D5943

rust: less set lookups in AncestorsIterator This uses the boolean return of `HashSet::insert()` to factor pairs of contains()/insert() into a single insert() On the mozilla-central repository (450k changesets), I get about a bit more than 10% better medians in perfancestors (taking the mean of three runs) Best run for parent changeset: ! wall 0.106474 comb 0.110000 user 0.110000 sys 0.000000 (median of 93) Best run for this changeset: ! wall 0.093191 comb 0.090000 user 0.090000 sys 0.000000 (median of 100) Differential Revision: https://phab.mercurial-scm.org/D5942

obsutil: don't assume leftctx and rightctx repo as same Backed out changeset 520514af2d93. hgsubversion can pass leftctx and rightctx which are instances of two different repositories. This was making tests fail on hgsubversion with 4.9. The two different instances are: (Pdb) p rightctx.repo() <filteredrepo:served <hgsubversion.svnrepo.svnlocalrepo object at 0x7fe29d296d10>> (Pdb) p leftctx.repo() <filteredrepo:visible <hgsubversion.svnrepo.svnlocalrepo object at 0x7fe29d494590>> Differential Revision: https://phab.mercurial-scm.org/D5968