mq: ban \r and \n in patch names (issue4711) This is at best crazy, and at worst will break things like the series file. Let's just stop the madness.

mq: use %r to format illegal characters instead of manually quoting This will make it easier to ban \r and \n in the next patch and still have a sensible error message.

histedit: abort rather than edit a public changeset (issue4704) This is suboptimal as the user still has to explicitly cancel the histedit afterwards, but it prevents the immediate problem. histedit should probably implicitly do 'hg histedit --abort' if a util.Abort is raised internally.

test-histedit-edit: add test that demonstrates bug in issue4704 Durham and I agree that it's a bug you can fold into a change that's not listed in the histedited set, so we'll follow this up with a change that prevents folds as the first edit step.