test: fix a phase divergence test case to actually not contains conflict The previous test case had a conflict, but that conflict is currently not raise by phase divergence resolution. This is an independent bug to solve.

tests: use current instability names everywhere

test: apply unstability resolution to `test-unstability-resolution-result.t` The test cases in this file probably deserved to be dispatched in other more thematic test file.

test: rename and clarify content of test-unstable-content-divergent.t The troubles → instabilities renaming was not applied here.

test: rename and clarify content of test-unstable-orphan.t The troubles → instabilities renaming was not applied here.

evolve: refactor the code which swap two nodes (in divergence resolution) I see that we are using the code to swap the "divergent" and "other" node; and updating the evolvestate accordingly at many places in divergence resolution. This patch extract that code to a function. Although I don't have strong opinion on this patch. It's a volunteered patch to remove some redundancy.

evolve: remove tmpctx arg from _resolvephasedivergent() Before this patch, in _resolvephasedivergent() function we were passing an optional argument "tmpctx" which was used to store a rebased version of bumped if required. But for sake of simplicity we can achieve the same results even without passing this "tmpctx" into that function. No changes in test files demonstrate that this patch don't break anything.