match: allow pats to be None match.match already interprets "!bool(patterns)" as matching everything (but includes and excludes still apply). We might as well allow None, which lets us simplify some callers a bit. I originally wrote this patch while trying to change match.match(patterns=[]) to mean to match no patterns. This patch is one step towards that goal. I'm not sure it'll be worth the effort to go all the way there, but I think this patch still makes sense on its own.