help: make help_unknown_ref() NORETURN

Announce that calling help_unknown_ref() exits the program.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

help.c

@@ -774,7 +774,8 @@ static struct string_list guess_refs(const char *ref)
 	return similar_refs;
 }
 
-void help_unknown_ref(const char *ref, const char *cmd, const char *error)
+NORETURN void help_unknown_ref(const char *ref, const char *cmd,
+			       const char *error)
 {
 	int i;
 	struct string_list suggested_refs = guess_refs(ref);

help.h

@@ -43,7 +43,7 @@ void list_commands(unsigned int colopts, struct cmdnames *main_cmds, struct cmdn
  * call this to die(), when it is suspected that the user mistyped a
  * ref to the command, to give suggested "correct" refs.
  */
-void help_unknown_ref(const char *ref, const char *cmd, const char *error);
+NORETURN void help_unknown_ref(const char *ref, const char *cmd, const char *error);
 
 static inline void list_config_item(struct string_list *list,
 				    const char *prefix,