Force-update feeds that haven't been modified for too long?

[Minoru]

Over on our mailing list, Francesco Ariis reports a server that doesn't update Last-Modified header, fooling Newsbeuter into believing that the document haven't been changed even though in fact, it's updated daily.

Technically, it's not Newsbeuter's problem, but we should consider providing a remedy that will let users get their news.

One idea I have right now is dropping condition headers (If-Modified-Since and If-None-Matches) once in a while. The trick is to make it small enough to be useful but still large enough so not to incur much bandwidth waste, and, if at all possible, affect properly behaving feeds as little as possible.