backout: provide linear backout as a default (without --merge option) This changes backouts changeset to retain linear history, .e. it is committed as a child of the working directory parent, not the reverted changeset parent. The default behavior was previously to just commit a reverted change as a child of the backed out changeset - thus creating a new head. Most of the time, you would use the --merge option, as it does not make sense to keep this dangling head as is. The previous behavior could be obtained by using 'hg update --clean .' after a 'hg backout --merge'. The --merge option itself is not affected by this change. There is also still an autocommit of the backout if a merge is not needed, i.e. in case the backout is the parent of the working directory. Previously we had (pwd = parent of the working directory): pwd older backout auto merge backout --merge auto commit With the new linear approach: pwd older backout auto commit backout --merge auto commit auto: commit done by the backout command merge: backout also already committed but explicit merge and commit needed commit: user need to commit the update/merge