Fix another date order bug

_plugins/courses_pages_generator.rb

@@ -44,9 +44,8 @@ module Jekyll
 		def get_course_editions(site, slug)
 			editions = site.data["courses"].values
 			editions = editions.select { |obj| obj["course"] == slug }
-			editions.sort_by { |obj| obj["date"] }
-			editions = editions.map { |obj| parse_edition_data(obj) }
-			editions
+			editions.sort { |a,b| a["date"] <=> b["date"] }
+			editions.map { |obj| parse_edition_data(obj) }
 		end
 
 		def make_past_editions_page(site, dir, course, editions)