relativedate: Deal with clock skew.

If the server has a clock running a bit ahead of the web browsing client,
relativedate could cause somewhat confusing displays like "3 seconds from now"
for just posted things.

As a hack, avoid displaying times in the future if they're less than a
small slip forward. I chose 30 minutes because both client and server could
be wrong in different directions, while it's still close enough that "just
now" is not horribly wrong.

debian/changelog

@@ -7,6 +7,7 @@ ikiwiki (3.11) UNRELEASED; urgency=low
     allowing the admin to see it during wiki setup.
     Closes: #520015
   * websetup: If setup fails, restore old setup file.
+  * relativedate: Deal with clock skew.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 21 Apr 2009 21:41:38 -0400
 

underlays/javascript/relativedate.js

@@ -45,6 +45,12 @@ function relativeDate(date) {
 	var offset = date.getTime() - now.getTime();
 	var seconds = Math.round(Math.abs(offset) / 1000);
 
+	// hack to avoid reading just in the future if there is a minor
+	// amount of clock slip
+	if (offset >= 0 && seconds < 30 * timeUnits['minute']) {
+		return "just now";
+	}
+
 	var ret = "";
 	var shown = 0;
 	for (i = 0; i < timeUnitOrder.length; i++) {