Redmine #5557: Fix files promises having wrong status report.

In functions where we invoke sub promises, we need to start with the
assumption that the promise will be skipped, instead of it being a
kept promise. The reason is that the skipped status has the lowest
priority, so if we end up skipping a promise, the status will still be
kept if that's what we started with.

https://cfengine.com/dev/issues/5557