Actually fix the url generation

src/lua/util.lua

@@ -110,6 +110,24 @@ function util.encode_id(number)
 	until number == 0
         return table.concat(result)
 end
+--[[
+Legacy code, try to encode with invalid characters in the url first
+]]
+local new_encode = util.encode_id
+function util.encode_id(number)
+	if number >= config.legacy_url_cutoff then
+		return new_encode(number)
+	else
+		local result = {}
+		local charlen = string.len(url_characters_legacy)
+		repeat
+			local pos = (number % charlen) + 1
+			number = math.floor(number / charlen)
+			table.insert(result,string.sub(url_characters_legacy,pos,pos))
+		until number == 0
+		return table.concat(result)
+	end
+end
 
 --[[
 Given a short HTML-safe url path, convert it to a storyid