Fixed tests

Author: ipepe

lib/wpxf/core/payload.rb

@@ -126,7 +126,7 @@ def enqueue_command(cmd)
     private
 
     def raw_payload_with_random_var_names
-      payload = "#{php_preamble} #{raw}"
+      payload = "#{php_preamble} #{raw}".dup
       vars = generate_vars(obfuscated_variables)
       obfuscated_variables.each { |v| payload.gsub!("$#{v}", "$#{vars[v]}") }
       payload