patch 8.2.2819: finishing an abbreviation with multi-byte char may not work

Problem:    Finishing an abbreviation with a multi-byte char may not work.
Solution:   Escape K_SPECIAL in the typed character. (closes #8160)

src/map.c

@@ -1540,10 +1540,23 @@ check_abbr(
 			tb[j++] = Ctrl_V;	// special char needs CTRL-V
 		    if (has_mbyte)
 		    {
+			int	newlen;
+			char_u	*escaped;
+
 			// if ABBR_OFF has been added, remove it here
 			if (c >= ABBR_OFF)
 			    c -= ABBR_OFF;
-			j += (*mb_char2bytes)(c, tb + j);
+			newlen = (*mb_char2bytes)(c, tb + j);
+			tb[j + newlen] = NUL;
+			// Need to escape K_SPECIAL.
+			escaped = vim_strsave_escape_csi(tb + j);
+			if (escaped != NULL)
+			{
+			    newlen = STRLEN(escaped);
+			    mch_memmove(tb + j, escaped, newlen);
+			    j += newlen;
+			    vim_free(escaped);
+			}
 		    }
 		    else
 			tb[j++] = c;

src/testdir/test_mapping.vim

@@ -1402,4 +1402,13 @@ func Test_script_local_remap()
   bwipe!
 endfunc
 
+func Test_abbreviate_multi_byte()
+  new
+  iabbrev foo bar
+  call feedkeys("ifoo…\<Esc>", 'xt')
+  call assert_equal("bar…", getline(1))
+  iunabbrev foo
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2819,
 /**/
     2818,
 /**/