merge: let manifestmerge emit 'keep' actions when keeping wd version Such a 'keep' action will later be the preferred (non)action when there is multiple ancestors. It is thus very convenient to have it explicitly. The extra actions will only be emitted in the case where the local file has changed since the ancestor but the other hasn't. That is the symmetrical operation to a 'get' action. This will create more action tuples that not really serve a purpose. The number of actions will however have the number of changed files as upper bound and it should thus not increase the memory/cpu use significantly.