### 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
toolbar_hbc->add_child(current_path_line_edit);
	button_reload = memnew(Button);
	button_reload->connect("pressed", callable_mp(this, &FileSystemDock::_rescan));
	button_reload->set_focus_mode(FOCUS_NONE);
	button_reload->set_tooltip_text(TTR("Re-Scan Filesystem"));
	button_reload->hide();
	toolbar_hbc->add_child(button_reload);
	button_toggle_display_mode = memnew(Button);
	button_toggle_display_mode->set_toggle_mode(true);
	button_toggle_display_mode->connect("toggled", callable_mp(this, &FileSystemDock::_toggle_split_mode));
	button_toggle_display_mode->set_focus_mode(FOCUS_NONE);
	button_toggle_display_mode->set_tooltip_text(TTR("Toggle Split Mode"));
	button_toggle_display_mode->set_flat(true);
	toolbar_hbc->add_child(button_toggle_display_mode);
	toolbar2_hbc = memnew(HBoxContainer);
	toolbar2_hbc->add_theme_constant_override("separation", 0);
	top_vbc->add_child(toolbar2_hbc);
	tree_search_box = memnew(LineEdit);
	tree_search_box->set_h_size_flags(SIZE_EXPAND_FILL);
	tree_search_box->set_placeholder(TTR("Filter Files"));
	tree_search_box->connect("text_changed", callable_mp(this, &FileSystemDock::_search_changed).bind(tree_search_box));
	toolbar2_hbc->add_child(tree_search_box);
	tree_button_sort = _create_file_menu_button();
	toolbar2_hbc->add_child(tree_button_sort);
	file_list_popup = memnew(PopupMenu);
	add_child(file_list_popup);
	tree_popup = memnew(PopupMenu);
	add_child(tree_popup);
	split_box = memnew(VSplitContainer);
	split_box->set_v_size_flags(SIZE_EXPAND_FILL);