This is simpler than temporary file version. There some minor test
changes since commit messages are no longer modifed. There is still
some tests using --commands with a real file.
Have histedit record the hex of the original changeset as already done by:
- graft
- commit --amend
- rebase
My main motivation for adding this is to prevent the creation of obsolescence cycle
(see issue3681).
Note that commit created during edit are not affected yet.
The old and fragile patching logic is replaced by smart merges (as rebase and
graft do). This should prevents some conflicts and smoother human resolution.
For this purpose the "foldchanges" function is renamed to "applychanges" and
handle a single revision only.
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.
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.
