obsolete: handle rebase --collapse
Recording obsolete in concludenode() did not work for --collapse because
only the first revision was passed to the call. The new strategy is to
track the rebase state in defineparents() and concludenode() and to
create markers only after a successful non-abort call. In theory, this
should also fix --continue/--abort cases.
The change in test-stabilize-order.t comes from concludenode() no longer
creating obsolete marker. stabilize command was actually duplicating
markers, once in concludenode(), once explicitely.
6c6bb7a23bb5125bf06da73265f039dd3447dafa 0.1.0