merge: consider successor changesets for a bare update Previously, a bare update would ignore any successor changesets thus potentially leaving you on an obsolete head. This happens commonly when there is an old bookmark that hasn't been moved forward which is the motivating reason for this patch series. Now, we will check for successor changesets if two conditions hold: 1) we are doing a bare update 2) *and* we are currently on an obsolete head. If we are in this situation, then we calculate the branchtip of the successor set and update to that changeset. Tests coverage has been added.

merge: refactor initialization of variables in update There is no code change here but this helps prepare for future commits that will fix a bare update with obsolete markers.

merge: update comment for future devs

obsolete: clarify documentation for succcessorssets

backout: add a message after backout that need manual commit In some case Backout silently succeeded to back out but left all the change uncommitted. This may be confusing for user so this changeset add a note reminding to commit. Other backout case already actively informs the user about created commit.

backout: avoid update on simple case. Before the changeset the backout process was: 1) go to <target> 2) revert to <target> parent 3) update back to changeset we came from The two update steps can takes a very long time to move back and forth unrelated file change between <target> and current working directory. The new process is just merging current working directory with the parent of <target> using <target> as ancestor. This give the very same result but skip the two updates. On big repo with a lot of files and changes that save a lots of time (x20 for one week window). The "merge" version (hg backout --merge) is still done with upgrades. We could imagine using in memory commit to speed it up but this is another fish.