revlog: use size_t for nodetree capacity This allows handling revlog containing more than 33554432 (INT_MAX / sizeof(nodetreenode)) revisions on x64 platforms. Differential Revision: https://phab.mercurial-scm.org/D9745

upgrade: demonstrate that a no-op upgrade still performs everything An upgrade operation which is not adding or removing anything should ideally error out. However, it does the whole cloning and everything. Next patch will fix it. Differential Revision: https://phab.mercurial-scm.org/D9694

upgrade: migrated -> upgraded in ui messages Differential Revision: https://phab.mercurial-scm.org/D9676

upgrade: remove unnecessary `is None` check `upgrade_engine.upgrade()` always return the `backuppath` value and there are not early returns. Hence I don't see how `backuppath` can be None. Adding extra unncessary safe checks hides unknown bugs. Hence removing it. Differential Revision: https://phab.mercurial-scm.org/D9675

engine: refactor code to replace stores in separate function In not all upgrades, we need to change the whole store. For example, when upgrading repository to share-safe mode, we don't touch revlogs at all hence store cloning and copying is not required. The store replacing code needs to be made aware about what all has changed and hence only copy/rename those things. To kickstart that, this patch moves existing logic into a separate function. Differential Revision: https://phab.mercurial-scm.org/D9674

engine: make hook point for extension a public function Well there are no private public functions in Python, but we generally treat functions and variables starting with `_` as private ones. A function which needs to be overrided in extension should be a public one. Differential Revision: https://phab.mercurial-scm.org/D9672

engine: prevent multiple checking of re-delta-multibase The _perform_clone function is called for each revlog cloned, hence we should prevent this function call overhead. Differential Revision: https://phab.mercurial-scm.org/D9669

engine: pass upgrade operation inside `_perform_clone()` Same as previous patch. Differential Revision: https://phab.mercurial-scm.org/D9668