* lisp/international/mule-cmds.el (encode-coding-char): Fix ASCII case

Don't bother with string-as-multibyte since `string` already returns
multibyte when needed.  Don't forget to encode when the string is
ASCII, e.g. for ebcdic case and to make sure we always return
a unibyte string.

* test/lisp/international/mule-tests.el (mule-cmds-tests--encode-ebcdic):
New test.

1 files changed, 5 insertions, 5 deletions

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index 27296ecfb2c..ecdab5e931d 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -2913,13 +2913,13 @@ If there's no description string for VALUE, return nil."
 If CODING-SYSTEM can't safely encode CHAR, return nil.
 The 3rd optional argument CHARSET, if non-nil, is a charset preferred
 on encoding."
-  (let* ((str1 (string-as-multibyte (string char)))
-	 (str2 (string-as-multibyte (string char char)))
+  (let* ((str1 (string char))
+	 (str2 (string char char))
 	 (found (find-coding-systems-string str1))
 	enc1 enc2 i1 i2)
-    (if (and (consp found)
-	     (eq (car found) 'undecided))
-	str1
+    (if (eq (car-safe found) 'undecided) ;Aka (not (multibyte-string-p str1))
+        ;; `char' is ASCII.
+	(encode-coding-string str1 coding-system)
       (when (memq (coding-system-base coding-system) found)
 	;; We must find the encoded string of CHAR.  But, just encoding
 	;; CHAR will put extra control sequences (usually to designate