为什么Emacs抱怨有风险的文件局部变量？

Question

尝试在GNU Emacs 24.5.1中使用purescript-mode，每当我在purescript文件中返回换行符时，Emacs都会打开一个新窗口告诉我：

purescript-mode-hook is a variable defined in `purescript-mode.el'.
Its value is (capitalized-words-mode)
Original value was nil

This variable may be risky if used as a file-local variable.

经过一些研究，我将以下内容添加到了.emacs文件中：

(add-to-list 'safe-local-variable-values 
  '(purescript-mode-hook . capitalized-words-mode))

现在，当我在purescript文件中返回换行符时，Emacs仍然会打开一个新窗口告诉我：

purescript-mode-hook is a variable defined in `purescript-mode.el'.
Its value is (capitalized-words-mode)
Original value was nil

  This variable may be risky if used as a file-local variable.
  However, you have added it to `safe-local-variable-values'.

如果我已明确告知Emacs它是安全的，为什么它仍在抱怨？如何抑制这种行为？