ok naddy

This has been shown to prevent mis-merges in some cases. It's probably not a final solution. We should look at what Git's "recursive merge" is doing and implement something similar. Keep using Myers during update/unstage. The advantage of Myers is that it produces smaller conflict chunks, and there are no known cases of mis-merges which affect update/unstage.

ok tracey

This was a long-standing and very annoying bug. The two xfail tests in the cherrypick test suite are passing now.

This fixes spurious 'U' notifications for symlinks during 'got update' that occurred even when the work tree was fully up-to-date. Observed on a work tree of the FreeBSD src repo and reproduced in our test suite by adding a no-op update at the end of a test which deals with updating symlinks.

found by naddy ok naddy jrick

Create automatic "backup" references which ensure that objects from the pre-rebase or pre-histedit state remain in the repository. A new -l option for 'got rebase' and 'got histedit' lists old commits. This makes it easier to recover from botched rebase or histedit operations. Removal of such objects currently requires got ref -d and git-gc. This will be made more convenient in the future. testing and ok jrick