patch 8.2.2603: Vim9: no effect if user command is also a function

Problem:    Vim9: no effect if user command is also a function.
Solution:   Check for paren following. (closes #7960)

src/testdir/test_vim9_cmd.vim

@@ -364,9 +364,8 @@ def Test_method_call_linebreak()
         return F()
       enddef
       def Test()
-        Foo
-          ->Bar()
-          ->setline(1)
+        Foo  ->Bar()
+             ->setline(1)
       enddef
       Test()
       assert_equal('the text', getline(1))
@@ -401,8 +400,7 @@ def Test_method_call_linebreak()
           return F()
       enddef
 
-      Foo
-         ->Bar()
+      Foo->Bar()
          ->setline(1)
   END
   CheckScriptSuccess(lines)
@@ -424,6 +422,33 @@ def Test_method_call_whitespace()
   CheckDefAndScriptSuccess(lines)
 enddef
 
+def Test_method_and_user_command()
+  var lines =<< trim END
+      vim9script
+      def Cmd()
+        g:didFunc = 1
+      enddef
+      command Cmd g:didCmd = 1
+      Cmd
+      assert_equal(1, g:didCmd)
+      Cmd()
+      assert_equal(1, g:didFunc)
+      unlet g:didFunc
+      unlet g:didCmd
+
+      def InDefFunc()
+        Cmd
+        assert_equal(1, g:didCmd)
+        Cmd()
+        assert_equal(1, g:didFunc)
+        unlet g:didFunc
+        unlet g:didCmd
+      enddef
+      InDefFunc()
+  END
+  CheckScriptSuccess(lines)
+enddef
+
 def Test_skipped_expr_linebreak()
   if 0
     var x = []