stablerange: introduce a basic-mergepoint method This method use the new 'mergepoint' based stable sorting. It is expected to be eventually better than branch point to stable range: more stable, easier to cache, etc. Having a basic implementation will allow use to validate more advanced implementation.

stablesort: add a new test to check for fully independant branches Apparently, this was not covered.

stablesort: add a --limit argument This will be useful when using stable sort within stable range.

stablesort: introduce a mergepoint based method focused on head The things we needs for stable range is head centric. So we simplify the issue by focussing on head.

stablesort: introduce a "mergepoint" method The mergepoint method decide order from merge. This allow to directly reuse a the full sort of one of the parent, and should simplify caching.

stablerange: fallback to a more naive approach to find subrange As suspected, using "bheads" was bit good enough in some case and we have to fall back to the approach used in "basic". On the evolve repo (about 3K changeset) this approach is about 60% slower than the previous (wrong) code.

stablebranch: avoid overlap between subrange Subrange overlap make things more complicated and less efficient. We fix the computation done in the "cached" version of the stablerange cache. This bring things in line with the result produced by the basic version. Since we already bumped the format version since the last release, I don't things we need to do anything else.

stablerange: introduce an 'basicstablerange' This class hold all the basic of stable range but the part specific to the sorting. This allow to clearly express what is expected from each method and to generate tests output to be validated against the more complex implementation. While writing this, we spotted a bug in the current stable range implementation. Fix coming.

stablerange: extract the core API into a 'stablerangecore' class To clarify what the code is doing without all the caching and algorithmic improvement, we extract a core class that highlight the basic API expected from the class.

stable-branch: setup tests to use a specific method by default This will make future test simpler.

stablerange: rework the debug command to allow for multiple method Similar to what we did for the other debug command related to sorting, we prepare for the arrival of multiple method to produce the result (including simple implementation that are easy to read but do not scale).

deptcache: make sure we warm the dept cache before warming the obsdiscovery The depthcache need to a warmed a bit more agressively

stablesort: add a 'method' argument to the debugstablesort command Let start experimenting with other way to do stable sorting.

stablesort: rename function to stablesort_branchpoint We are about to test different approach to stable sorting. We clarify that the existing method is sorting from branch points.

stablerange: update the filename to avoid cache confusion The schema validation seems to not work as well as intended, we update the file name to make sure there will be no confusion.

stablesort: extract in its own module We are going to introduce variants, cache and more complex logic, we move that in its own repository beforehand.

compat: in depth cache, only use cachevfs when available We support older version without the new vfs.

depthcache: issue a progress bar when loading the depth cache The operation can be in the minute order of magnitude of some larger repository. We better keep the user entertain when he wait.

depthcache: move to a dedicated object and storage The SQL cache was overkill and fragile. We move to a dedicated storage using the new generic class.

cache: adds debug details about what the content of the update Having more data in debug is good, we add a small method to help providing them. This code was headed for core during the 4.3 cycle but never made it there. So we starts with a copy in the evolve repository.

cache: introduce a changelogsourcebase class This abstract class will help code that need a cache tracking the changelog content (eg: the branchmap cache). The cache key used is the same as what the branchmap uses. This code was headed for core during the 4.3 cycle but never made it there. So we starts with a copy in the evolve repository.

cache: introduce an abstract class for cache we can upgrade incrementally Right now each class implements their own mechanism for validation, and update. We start introducing abstract class to ultimately allow more unification of the cache code. The end goal of this series is to introduce a cache for some obsolescence property, not to actually implement the cache. However, taking advantage of adding a new cache to introduce the abstract class seems like a win. This code was headed for core during the 4.3 cycle but never made it there. So we starts with a copy in the evolve repository.

depth: basic debugdepth implementation and test This will come very handy to validate more advanced implementation later.

topics: add a config to reject draft changeset without topic on a server This patch adds a new config option experimental.topic-mode.server which if sets to True, the server won't accept any draft changeset without topic on it. In case both `experimental.topic-mode.server` and `experimental.topic.publish-bare-branch` are set to True, the enforce-topic one is respected. Tests are added for it. The CHANGELOG file is also updated mentioning about the config option.