Simplify url-encode-url and add a test

* lisp/url/url-util.el (url-encode-url): Simplify.
url-generic-parse-url copes with multibyte strings just fine
(https://debbugs.gnu.org/cgi/bugreport.cgi?bug=24117#185).

* test/lisp/url/url-parse-tests.el
(url-generic-parse-url/multibyte-host-and-path): New test.

lisp/url/url-util.el

@@ -450,13 +450,10 @@ This function also performs URI normalization, e.g. converting
 the scheme to lowercase if it is uppercase.  Apart from
 normalization, if URL is already URI-encoded, this function
 should return it unchanged."
-  (if (multibyte-string-p url)
-      (setq url (encode-coding-string url 'utf-8)))
   (let* ((obj  (url-generic-parse-url url))
 	 (user (url-user obj))
 	 (pass (url-password obj))
-	 (host (url-host obj))
-	 (path-and-query (url-path-and-query obj))
+         (path-and-query (url-path-and-query obj))
 	 (path  (car path-and-query))
 	 (query (cdr path-and-query))
 	 (frag (url-target obj)))
@@ -464,12 +461,6 @@ should return it unchanged."
 	(setf (url-user obj) (url-hexify-string user)))
     (if pass
 	(setf (url-password obj) (url-hexify-string pass)))
-    ;; No special encoding for IPv6 literals.
-    (and host
-	 (not (string-match "\\`\\[.*\\]\\'" host))
-	 (setf (url-host obj)
-               (decode-coding-string (url-host obj) 'utf-8)))
-
     (if path
 	(setq path (url-hexify-string path url-path-allowed-chars)))
     (if query

test/lisp/url/url-parse-tests.el

@@ -162,6 +162,11 @@
   (should (equal (url-generic-parse-url "#") (url-parse-make-urlobj nil nil nil nil nil "" "" nil nil)))
   (should (equal (url-generic-parse-url "#foo") (url-parse-make-urlobj nil nil nil nil nil "" "foo" nil nil))))
 
+(ert-deftest url-generic-parse-url/multibyte-host-and-path ()
+  (should (equal (url-generic-parse-url "http://банки.рф/фыва/")
+                 (url-parse-make-urlobj "http" nil nil "банки.рф" nil
+                                        "/фыва/" nil nil t))))
+
 (provide 'url-parse-tests)
 
 ;;; url-parse-tests.el ends here