Fix escaping of links in html export.

* lisp/ox-html.el (org-html-link): Unescape org-escaped links an
  re-escape for html (browser).

lisp/ox-html.el

@@ -2624,7 +2624,9 @@ INFO is a plist holding contextual information.  See
 	 (path
 	  (cond
 	   ((member type '("http" "https" "ftp" "mailto"))
-	    (concat type ":" raw-path))
+	    (org-link-escape
+	     (org-link-unescape
+	      (concat type ":" raw-path)) org-link-escape-chars-browser))
 	   ((string= type "file")
 	    ;; Treat links to ".org" files as ".html", if needed.
 	    (setq raw-path