compat: import the module dagutil module in evolve Discovery code is core have been rewritten to no longer depends on dagutil and the module have been removed. This break evolve's obsmarker discovery (older version of the discovery use the same concept).. A quick work around is to import the dagutil module in evolve and use that for now.

evolve: delete evolvestate after aborting interrupted `next --evolve` We didn't use to delete the evolvestate after aborting an interrupted `next --evolve`. This patch makes sure we do that. The test changes demonstrate the fix and we add a CHANGELOG entry about the fix.