evolve: add test which demonstrate issue6113 This patch introducing a new test file which contains the test for issue6113 which is `test-evolve-content-divergent-distributed.t`. This test file is supposed to contain tests for distributed workflows. Next patch will fix the bug.

test: consolidate the content-divergent test cases This commit move most of the content divergent related test in dedicated and thematic test files.

changelog: mention the fix to issue6057

extensions: avoid enabling evolve for unrelated repositories (issue6057) The support for the `experimental.evolve` config have been there forever. So we can stop using the global variable. This help avoiding evolve to enable itself of repository that did not explicitly activated it. For example, this is useful for hgwebdir. Before this change, evolution feature had to be explicitly disabled or enabled in every single repository.

stack: improve set combination logic

stack: fix phasecache._phasesets check logic When _phasesets is not None, it's a list, and it contains set()s of revisions in a specific phase, starting from public, draft, secret and so on. But since repos are supposed to have the majority of revisions in public phase, the first element of this list is not a (potentially huge) set, but None. Previously this code tried to check if there's any element that is None, and was always finding None at index 0, so the short path was executed every time and the rest of the function was never used.

evolve: remove todo markers from a test which has been fixed

next: clarify tests related to `commands.update.check` test This clarify the test and help understand the next changeset.

stack: simplify phasecache checks in _stackcandidates()

evolve: fix divergence resolution when not merging a descendant In divergence resolution, when we merge other cset with divergent one we pass a `mergeancestor` arg to merge.update() and before this patch we were passing `mergeancestor` as True in every case. But it should be True only when we are merging a descendant onto an ancestor. When mergeancestor is True it does two things: 1) allows the merge if the destination is the same as the parent of the ctx (so we can use graft to copy commits) 2) informs update that the incoming changes are newer than the destination so it doesn't prompt about "remote changed foo which local deleted". So this patch change it to pass `mergeancestor` as True only when it is required. And changes in test file shows that it wasn't prompting either in those cases when it should (acc. to 2nd point) Test written by Pierre-Yves David, based the one updated in 5dbaabfe2c59.