> Behavioral changes happen, and maybe we don't even support some feature any more. There's a number of fields in /proc/<pid>/stat that are printed out as zeroes, simply because they don't even exist in the kernel any more, or because showing them was a mistake (typically an information leak). But the numbers got replaced by zeroes, so that the code that used to parse the fields still works. The user might not see everything they used to see, and so behavior is clearly different, but things still _work_, even if they might no longer show sensitive (or no longer relevant) information.
I'm not sure I prefer the described result. If my application depends on some of those zero'd fields, it seems like that has potential to cause serious debugging problems, as opposed to just causing an error on the parse.