histedit-test: ensure that non commute test will never commute The previous version would commute if using merge algorithm (to be accurate, merge will cleanly prompt the user during the merge). The new version create and initial commit with some content for all involved files en ensure all changes are a content changes of the first lines. This lead to guaranteed conflict when commuted.

histedit: display action being processed in debug mode This is very useful when debugging histedit.

histedit: fold in memory Update the folding code to works in memory instead of applying patches on the working directory. This is cleaner, faster and prepare the removal of the whole patching logic. This new collapse function will probably move into core sooner or later. A lot of other rewriting operation may benefit from it.

histedit: move makedesc function near other rules related function Having it in the middle of action logic is confusing

histedit: move `between function` outside the action logic Having this function in the middle of action and patching logic did not make sense

histedit document the makedest function