evolve: store obsmarkers to be deleted in evolvestate There are operations which don't create a new node rather they just obsolete one of the unstable node in favour of existing one. In such cases if a further resolution leads to conflicts and user calls `evolve --abort` or `evolve --stop`, we might need to delete that obsmarker. So let's store such obsmarkers in the evolvestate.

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test-drop.t

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test-inhibit.t

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test-simple4server.t

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tests/test-simple4server-bundle2.t