shelve: no longer strip internal commit when using internal phase When the internal phase is used, the internal commits we create during shelve will be automatically hidden, and we don't need to strip them. Avoiding strips gives much better performances and is less traumatic for caches. Test changes are all related to revision numbers increasing more quickly since we avoid stripping. At the end of `test-shelve.t` we now need manually strip the shelve-commit in addition to the x.shelve file deletion. This emulates a preexisting shelve after a repository upgrade. Note: The hidden internal commits confuses rebase a bit as shown by a new test added. This will happen when the user have shelve commits on top of a changeset to be rebased. We'll fix this in the next commit. As we still use a backup bundle, rebase can just strip the internal changesets and be fine.