phases: stop using `repo.set` in `remotephasessummary`
The `repository.set` create changectx on the fly, an expensive operation. Using
`repo.revs` and a direct rev-num → node-id translation will be significantly
faster.
This is especially true as we prepare ourself to no longer do the rev-num →
node-id transalation there.
The speedup is a bit lost in the overall noisyness of the slow phase discovery algorithm, but it save a small amount of time in my benchmark.
Test issue2761
$ hg init repo
$ cd repo
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1