Ignore tasks

lib/brakeman/app_tree.rb

@@ -71,7 +71,7 @@ module Brakeman
     end
 
     def lib_paths
-      @lib_files ||= find_paths("lib").reject { |path| path.include? "/generators/" }
+      @lib_files ||= find_paths("lib").reject { |path| path.include? "/generators/" or path.include? "lib/tasks/" }
     end
 
   private

test/apps/rails4/lib/tasks/some_task.rb

+class SomeTask
+  def some_task
+    # Should not warn because we are ignoring tasks
+    `#{x}`
+  end
+end