obsolete: unify collapsed revisions markers handling When collapsing A, B and C into D, amend was registering: A -> D B -> D A -> B C -> D A -> C while the rebase wrapper was doing: A -> D B -> D C -> D At this point, I have no argument to favor one or another or even a new one like: A -> B B -> C C -> D so I am aligning the rebase implementation on the older amend one. At least we can now change them all at once.

rebase: improve invalid revisions filtering - Filter rebasestate nullmerge and unrebased revision before considering updating obsolete. This simplifies the handling of obsolete and make it ignore unrebased revision rather than extinguishing them. - Apply obsolete markers only if rebasestate is not empty, testing rebasetarget was irrelevant.

test-evolve: extend output and exhibit an amend bug The extended section shows the parent revision stabilizing itself on another revision, without --any. In theory, only descendants of the parent predecessors or of its descendants should be stabilized, and be stabilized in parent subtree. Unfortunately, stabilize implementation correctly picks the changesets to stabilize but not their target. This problem is aggravated by amend registering too many obsolete markers which prevents the stabilize selection heuristic to prune several changesets.