### Godot version

v4.1.rc2.official [46424488e]

### System information

Godot v4.1.rc2 - Linux Mint 20 (Ulyana) - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2060 SUPER (nvidia; 515.105.01) - Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz (8 Threads)

### Issue description

Dragging and dropping a file to a new position inside its current folder, or onto the icon for its current folder - when that folder is the project root folder :res// - will be treated as though you were dropping a different file with the same name.

Expectation: for nothing to happen.

Also tried it in 4.0.3 and 4.1-dev3, where it behaves as expected.

https://github.com/godotengine/godot/assets/64640811/90de1120-dd92-41b8-b202-db77c343103a

### Steps to reproduce

1. New or existing project.
2. Click and drag a file in :res// in FileSystem dock.
3. Drop the file back into :res//.
4. Be prompted to overwrite or rename.

### Minimal reproduction project

N/A
for (int i = 0; i != FILE_SORT_MAX; i++) {
		tree_button_sort->get_popup()->set_item_checked(i, (i == (int)p_file_sort));
		file_list_button_sort->get_popup()->set_item_checked(i, (i == (int)p_file_sort));
	}
	file_sort = p_file_sort;
	
	_update_tree(get_uncollapsed_paths());
	_update_file_list(true);
}
void FileSystemDock::_file_sort_popup(int p_id) {
	set_file_sort((FileSortOption)p_id);
}
MenuButton *FileSystemDock::_create_file_menu_button() {
	MenuButton *button = memnew(MenuButton);
	button->set_flat(true);
	button->set_tooltip_text(TTR("Sort Files"));
	PopupMenu *p = button->get_popup();
	p->connect("id_pressed", callable_mp(this, &FileSystemDock::_file_sort_popup));
	p->add_radio_check_item(TTR("Sort by Name (Ascending)"), FILE_SORT_NAME);
	p->add_radio_check_item(TTR("Sort by Name (Descending)"), FILE_SORT_NAME_REVERSE);
	p->add_radio_check_item(TTR("Sort by Type (Ascending)"), FILE_SORT_TYPE);
	p->add_radio_check_item(TTR("Sort by Type (Descending)"), FILE_SORT_TYPE_REVERSE);
	p->add_radio_check_item(TTR("Sort by Last Modified"), FILE_SORT_MODIFIED_TIME);
	p->add_radio_check_item(TTR("Sort by First Modified"), FILE_SORT_MODIFIED_TIME_REVERSE);
	p->set_item_checked(file_sort, true);
	return button;
}
void FileSystemDock::_bind_methods() {