Fix loading data when no author_id is passed

app/controllers/autocomplete_controller.rb

@@ -15,7 +15,7 @@ class AutocompleteController < ApplicationController
         @users = [*@users, current_user]
       end
-      if params[:author_id]
+      unless params[:author_id] == "false"
         @users = [User.find(params[:author_id]), *@users]
       end

app/services/merge_requests/base_service.rb

@@ -23,8 +23,8 @@ module MergeRequests
     private
-    def filter_params(issueable = nil)
-      super(:merge_request, issueable)
+    def filter_params(issuable = nil)
+      super(:merge_request, issuable)
     end
   end
 end