Aliases canot be set if Update Action is : Do nothing

If the Update action is "do nothing" then aliases cannot be auto generated. If the Update action is anything else then aliases are forcibly changed. I needed a way to define aliases, have them stick, but also allow them to be auto generated. The settings help text indicates that the rule should NOT apply if there is NOT an alias but the code does not match that description. The attached patch aligns the code and the description.

While this resolves my problem I am not entirely happy with the solution. It is NOT backwards compatible and it is confusing. I am posting this here just in case someone else finds it useful. A potentially better solution is a hook that enables a 'maintain pathauto' option that self-manages paths that need to be and ignore those that must have a consistent URL.