copies: make two version of the changeset centric algorithm They are two main ways to run the changeset-centric copy-tracing algorithm. One fed from data stored in side-data and still in development, and one based on data stored in extra (with a "compatibility" mode). The `extra` based is used in production at Google, but still experimental in code. It is mostly unsuitable for other users because it affects the hash. The side-data based storage and algorithm have been evolving to store more data, cover more cases (mostly around merge, that Google do not really care about) and use lower level storage for efficiency. All this changes make is increasingly hard to maintain de common code base, without impacting code complexity and performance. For example, the compatibility mode requires to keep things at different level than what we need for side-data. So, I am duplicating the involved functions. The newly added `_extra` variants will be kept as today, while I will do some deeper rework of the side data versions. Long terms, the side-data version should be more featureful and performant than the extra based version, so I expect the duplicated `_extra` functions to eventually get dropped. Differential Revision: https://phab.mercurial-scm.org/D9114

changing-files: retrieve changelogrevision.files from the sidedata block The `files` field is know to have issue, using a list with fixed, and fixable, computation can only help. For example, using a fixes `files` field would be enough to fix issue6219 once this feature get usable in production. We focus on having thing working for now, we will deal with performance later. Right now we have a ironic situation were we parse sorted value from disk to turn them into a set and then having to sort it again. Differential Revision: https://phab.mercurial-scm.org/D9092

changing-files: drop the now useless changelogrevision argument Since all filename are now included in the sidedata block, we no longer need to decode the `files` from the revision. Differential Revision: https://phab.mercurial-scm.org/D9091

changing-files: rework the way we store changed files in side-data We need to store new data so this is a good opportunity to rework this fully. 1) We directly store the list of affected file in the side data: * This avoid having to fetch and parse the `files` list in the revision in addition to the sidedata. Making the data more self sufficient. * This work around situation where that `files` field contains wrong information, and open the way to other bug fixing (eg: issue6219) * The format (fixed initial index, sorted files) allow for fast lookup of filename within the structure. * This unify the storage of affected files and copies sources and destination, limiting the number filename stored redundantly. * This prepare for the fact we should drop the `files` as soon as we do any change affecting the revision schema. * This rely on compression to avoid a significant increase of the changelog.d. More testing on this will be done before we freeze the final format. 2) We can store additional data: * The new "merged" field, * A future "salvaged" set recording files that might have been deleted but have were still present in the final result. Differential Revision: https://phab.mercurial-scm.org/D9090

tests: skip doctests if not running from a hg repo Differential Revision: https://phab.mercurial-scm.org/D9150

py3: use native string when comparing with a function's argspec I only found two such bugs in `contrib/perf.py` Differential Revision: https://phab.mercurial-scm.org/D9149

test: try to unflaky test-profile.t That test rely on timing measurement, because it is about timing measurement. We try to filter out the most common source of flakyness (slow disk stating)

merge: check for conflicting actions irrespective of length of bids We should for whether bids contain a combination of actions which conflict with each other. Since right now we only have couple of such combination, and combinations also consist of two actions, we were checking for them only when length of bids is 2. Let's check that irrespective of the length of bids.

branching: merge with stable

log: extract function that builds (revs, makefilematcher) from walkopts "hg grep" and "hg churn" will use this interface.