FIX: prevent cross-contamination of emojis in multisites

app/assets/javascripts/discourse/lib/emoji/emoji.js.erb

@@ -12,6 +12,11 @@ Discourse.Dialect.registerEmoji = function(code, url) {
   extendedEmoji[code] = url;
 };
 
+// This method is used by PrettyText to reset custom emojis in multisites
+Discourse.Dialect.resetEmoji = function() {
+  extendedEmoji = {};
+};
+
 Discourse.Emoji.list = function(){
   var list = emoji.slice(0);
   _.each(extendedEmoji, function(v,k){ list.push(k); });

lib/pretty_text.rb

@@ -189,6 +189,8 @@ module PrettyText
         end
       end
 
+      # reset emojis (v8 context is shared amongst multisites)
+      context.eval("Discourse.Dialect.resetEmoji();")
       # custom emojis
       Emoji.custom.each do |emoji|
         context.eval("Discourse.Dialect.registerEmoji('#{emoji.name}', '#{emoji.url}');")