Arch Linux

Description:
cmake BoostConfig.cmake autoconfiguration breaks with boost 1.71 (config file is found, but target defines the non existend `/include` directory)

Additional info:
* package version(s)
* boost-1.69.0-2-x86_64 working
* boost-1.71.0-2-x86_64 not working working
* cmake version 3.15.4

Steps to reproduce:
touch main.cpp
echo -e "cmake_minimum_required(VERSION 3.15)\nproject(test)\nfind_package(Boost REQUIRED)\nadd_executable(test main.cpp)\ntarget_link_libraries(test PRIVATE Boost::headers)" > CMakeLists.txt
cmake -S . -B _build


output on 1.71.0-2
-- The C compiler identification is GNU 9.2.0
-- The CXX compiler identification is GNU 9.2.0
-- Check for working C compiler: /bin/cc
-- Check for working C compiler: /bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /bin/c++
-- Check for working CXX compiler: /bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Boost: /lib64/cmake/Boost-1.71.0/BoostConfig.cmake (found version "1.71.0")
-- Configuring done
CMake Error in CMakeLists.txt:
Imported target "Boost::headers" includes non-existent path

"/include"

in its INTERFACE_INCLUDE_DIRECTORIES. Possible reasons include:

* The path was deleted, renamed, or moved to another location.

* An install or uninstall procedure did not complete successfully.

* The installation package was faulty and references files it does not
provide.



CMake Error in CMakeLists.txt:
Imported target "Boost::headers" includes non-existent path

"/include"

in its INTERFACE_INCLUDE_DIRECTORIES. Possible reasons include:

* The path was deleted, renamed, or moved to another location.

* An install or uninstall procedure did not complete successfully.

* The installation package was faulty and references files it does not
provide.



-- Generating done
CMake Generate step failed. Build files cannot be regenerated correctly.