Merge branch 'js/rebase-orig-head-fix'

"git rebase" that was reimplemented in C did not set ORIG_HEAD correctly, which has been corrected. * js/rebase-orig-head-fix: built-in rebase: set ORIG_HEAD just once, before the rebase built-in rebase: demonstrate that ORIG_HEAD is not set correctly built-in rebase: use the correct reflog when switching branches built-in rebase: no need to check out `onto` twice