anchor.diff:  
   -- check for combination/required flags
   local function check_flags()
  +	if SELFCONTAINED then
  +		if not vars.PREFIX then
  +			die("Option /P is required when using /SELFCONTAINED")
  +		end
  +		if vars.SYSCONFDIR or vars.ROCKS_TREE or vars.SCRIPTS_DIR then
  +			die("Cannot combine /TREE, /SCRIPTS or /CONFIG with /SELFCONTAINED")
  +		end
  +	end
   	if INSTALL_LUA then
   		if vars.LUA_INCDIR or vars.LUA_BINDIR or vars.LUA_LIBDIR or vars.LUA_PREFIX then
   			die("Cannot combine option /L with any of /LUA /BIN /LIB /INC")
  
positive.code: 
  Configuring the destinations:
  /TREE [dir]    Root of the local tree of installed rocks.
                 Default is %PROGRAMDATA%\LuaRocks
  /SCRIPTS [dir] Where to install commandline scripts installed by
                 rocks. Default is {TREE}/bin.
  
  Configuring the Lua interpreter:
  /LV [version]  Lua version to use; either 5.1 or 5.2.
                 Default is 5.1
  
negative.code: local FORCE_CONFIG = false
  local INSTALL_LUA = false
  local USE_MINGW = false
  local REGISTRY = true
  local NOADMIN = false
  local PROMPT = true
  local SELFCONTAINED = false
  
  ---
  -- Some helpers
  