install( CODE/SCRIPT COMPONENT component "..."/file ) is ignored

CMakeLists.txt :

cmake_minimum_required(VERSION 3.16)
project(install_code C)
install( CODE "message (\"component unspecified\") " )
install( CODE COMPONENT comp "message (\"component comp\") " )

cmake_install.cmake :

if("x${CMAKE_INSTALL_COMPONENT}x" STREQUAL "xUnspecifiedx" OR NOT CMAKE_INSTALL_COMPONENT)
  message ("component unspecified") 
endif()

if(CMAKE_INSTALL_COMPONENT)
  set(CMAKE_INSTALL_MANIFEST "install_manifest_${CMAKE_INSTALL_COMPONENT}.txt")
else()
  set(CMAKE_INSTALL_MANIFEST "install_manifest.txt")
endif()

string(REPLACE ";" "\n" CMAKE_INSTALL_MANIFEST_CONTENT
       "${CMAKE_INSTALL_MANIFEST_FILES}")
file(WRITE "D:/dev/Bugs/cmake_code/build/${CMAKE_INSTALL_MANIFEST}"
     "${CMAKE_INSTALL_MANIFEST_CONTENT}")

dosn't contain "component comp" message.

$ mkdir build && cd build
$ cmake
....
$ cmake --install .
-- Install configuration: ""
component unspecified
$ cmake --install . --component comp
-- Install configuration: ""

Tested with cmake 3.16 to 3.20.2