patch 8.2.2317: Vim9: command modifier before list unpack doesn't work

Problem:    Vim9: command modifier before list unpack doesn't work.
Solution:   Only recognize "[" directly after the name. (closes #7641)

src/ex_docmd.c

@@ -2745,15 +2745,18 @@ parse_command_modifiers(
 	//   silent! verbose = func()
 	//   verbose.member = 2
 	//   verbose[expr] = 2
+	// But not:
+	//   verbose [a, b] = list
 	if (in_vim9script())
 	{
-	    char_u *s;
+	    char_u *s, *n;
 
 	    for (s = p; ASCII_ISALPHA(*s); ++s)
 		;
-	    s = skipwhite(s);
-	    if (vim_strchr((char_u *)".[=", *s) != NULL
-						 || (*s != NUL && s[1] == '='))
+	    n = skipwhite(s);
+	    if (vim_strchr((char_u *)".=", *n) != NULL
+		    || *s == '['
+		    || (*n != NUL && n[1] == '='))
 		break;
 	}
 

src/testdir/test_vim9_assign.vim

@@ -1481,6 +1481,12 @@ def Test_assign_command_modifier()
       assert_equal({one: 3}, topleft)
       leftabove topleft[' '] = 4
       assert_equal({one: 3, ' ': 4}, topleft)
+
+      var x: number
+      var y: number
+      silent [x, y] = [1, 2]
+      assert_equal(1, x)
+      assert_equal(2, y)
   END
   CheckDefAndScriptSuccess(lines)
 enddef

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2317,
 /**/
     2316,
 /**/