Allow 'file:' protocol for Info-follow-nearest-node.

etc/NEWS

@@ -84,6 +84,12 @@ work right without some adjustment:
 
 * Changes in Emacs 27.1
 
+---
+*** Info browser can follow ``file:'' protocol URL's URL created with
+The URL's created by the @url Texinfo command, and followed with the
+Info-follow-nearest-node function, can now have 'file:' prototype and
+are passed to 'browse-url' function, like were the other Web protocols
+(namely ftp, http, and https).
 ---
 ** New variable 'xft-ignore-color-fonts'.
 Default t means don't try to load color fonts when using Xft, as they

lisp/info.el

@@ -3938,8 +3938,8 @@ If FORK is a string, it is the name to use for the new buffer."
 If FORK is non-nil, it is passed to `Info-goto-node'."
   (let (node)
     (cond
-     ((setq node (Info-get-token (point) "[hf]t?tps?://"
-				 "\\([hf]t?tps?://[^ \t\n\"`‘({<>})’']+\\)"))
+     ((setq node (Info-get-token (point) "\\(?:f\\(?:ile\\|tp\\)\\|https?\\)://"
+				 "\\(\\(?:f\\(?:ile\\|tp\\)\\|https?\\)://[^ \t\n\"`‘({<>})’']+\\)"))
       (browse-url node)
       (setq node t))
      ((setq node (Info-get-token (point) "\\*note[ \n\t]+"