pytype: drop py3.6 support Pytype 2022.01.07 only supports 3.7+. Differential Revision: https://phab.mercurial-scm.org/D12400

perf-util: add a `compare-discovery-case` script This script run the same discovery case using multiple variants of the algorithm and report differences in behavior, especially regarding the numbers of roundtrip. Differential Revision: https://phab.mercurial-scm.org/D12399

discovery: also audit the number of queries done In addition to the number of roundtrip, we now also track the number of queries we perform, this is useful to assert the tradeoff between number of roundtrip and the number of queries. Differential Revision: https://phab.mercurial-scm.org/D12398

search-discovery-case: display more information about the interresting case We display information about the total number of revs and the common/missing numbers. This is useful to spot the interresting case. Differential Revision: https://phab.mercurial-scm.org/D12397

subsetmaker: rework the antichain generation to be usable Before this, antichain computation can run for 10s of hours without completion in sight. We use a more direct approach in the computation to keep the computation in complexity in check. With good result. We can now have a full antichain computation on mozilla-try in about one minute. Which is usable. Differential Revision: https://phab.mercurial-scm.org/D12396

subsetmaker: use SortedSet for the scratch variant This provides a massive speedup on wide repository with many heads. For example on mozilla-try, this move from un-usable slow to fairly instant. Differential Revision: https://phab.mercurial-scm.org/D12395

subsetmaker: stabilize the computation of `scratch` subset `heads` is set, order of the element are not deterministic and we need to stabilize that if we want to get reproducible results. Differential Revision: https://phab.mercurial-scm.org/D12394

revlog: recommit 49fd21f32695 with a fix for issue6528 `filelog.size` currently special cases two forms of metadata encoding: - copy data via the parent order as flag bit - censor data by peaking into the raw delta All other forms of metadata encoding including the empty metadata block are mishandled. In `basefilectx.cmp` the empty metadata block is explicitly checked to compensate for this. Restore 49fd21f32695, but disable it for filelog, so that the original flag bit use contines to work. Document all this mess for now in preparation of a proper rework. Differential Revision: https://phab.mercurial-scm.org/D11203