FIX: correct width expansion when appending char in range 128-255

resolves: Oldes/Rebol-issues#2486

Author: Oldes

src/core/f-modify.c

@@ -3,6 +3,7 @@
 **  REBOL [R3] Language Interpreter and Run-time Environment
 **
 **  Copyright 2012 REBOL Technologies
+**  Copyright 2012-2022 Rebol Open Source Contributors
 **  REBOL is a trademark of REBOL Technologies
 **
 **  Licensed under the Apache License, Version 2.0 (the "License");
@@ -157,7 +158,7 @@
 		else Trap_Arg(src_val);
 	}
 	else if (IS_CHAR(src_val)) {
-		if (VAL_CHAR(src_val) < 256) {
+		if (VAL_CHAR(src_val) < 128) {
 			src_ser = BUF_FORM;
 			*SERIES_DATA(src_ser) = (REBYTE)VAL_CHAR(src_val);
 		}

src/core/s-make.c

@@ -3,6 +3,7 @@
 **  REBOL [R3] Language Interpreter and Run-time Environment
 **
 **  Copyright 2012 REBOL Technologies
+**  Copyright 2012-2022 Rebol Open Source Contributors
 **  REBOL is a trademark of REBOL Technologies
 **
 **  Licensed under the Apache License, Version 2.0 (the "License");
@@ -246,7 +247,7 @@
 	bp = BIN_SKIP(dst, idx);
 	up = UNI_SKIP(src, pos);
 	for (n = 0; n < len; n++) {
-		if (up[n] > 0xFF) {
+		if (up[n] >= 0x80) {
 			//Debug_Num("##Widen-series because char value is:", up[n]);
 			// Expand dst and restart:
 			idx += n;

src/tests/units/port-test.r3

@@ -490,6 +490,13 @@ if system/platform = 'Windows [
 				not error? try [write clipboard:// c]
 				strict-equal? c try [read clipboard://]
 			]
+		--test-- "issue-2486"
+		;@@ https://github.com/Oldes/Rebol-issues/issues/2486
+			foreach ch [#"a" #"^(7F)" #"^(80)" #"^(A0)"][
+				write clipboard:// append copy "" ch
+				--assert (to binary! ch) = to binary! read clipboard://
+			]
+			
 	===end-group===
 ]