rebase: ensure rebase revision remains visible (issue4504) Before this changeset rebase was getting very confused if any revision in the rebase set became hidden. This was fairly easy to achieve if a rebased revision was made visible by the working copy location. The rebase process would update somewhere else and the revision would become hidden. To work around this issue, we ensure rebased revisions remain visible for the whole process. This is a simple change suitable for stable. More subtle usage of unfiltered repository in rebase may solve this issue more cleanly.