Merge branch 'jk/rebase-i-drop-ident-check' into maint

Even when "git pull --rebase=preserve" (and the underlying "git rebase --preserve") can complete without creating any new commit (i.e. fast-forwards), it still insisted on having a usable ident information (read: user.email is set correctly), which was less than nice. As the underlying commands used inside "git rebase" would fail with a more meaningful error message and advice text when the bogus ident matters, this extra check was removed. * jk/rebase-i-drop-ident-check: rebase-interactive: drop early check for valid ident