Merge branch 'lt/commit-tree-guess-utf-8'

Teach "git commit" and "git commit-tree" the "we are told to use utf-8 in log message, but this does not look like utf-8---attempt to pass it through convert-from-latin1-to-utf8 and see if it makes sense" heuristics "git mailinfo" already uses. * lt/commit-tree-guess-utf-8: commit/commit-tree: correct latin1 to utf-8