Merge branch 'mz/rebase-no-mbox'

Teach "am --rebasing" codepath to grab authorship, log message and the patch text directly out of existing commits. This will help rebasing commits that have confusing "diff" output in their log messages. * mz/rebase-no-mbox: am: don't call mailinfo if $rebasing am --rebasing: get patch body from commit, not from mailbox rebase --root: print usage on too many args rebase: don't source git-sh-setup twice