failing tests is_receiver_of

[100%] Building CXX object libs/core/execution_base/tests/unit/CMakeFiles/basic_receiver_test.dir/basic_receiver.cpp.o
/home/extended/hpx/libs/core/execution_base/tests/unit/basic_receiver.cpp:216:5: error: static_assert failed due to requirement 'is_receiver_of<mylib::receiver_1, hpx::execution::experimental::detail::compose_signatures<hpx::execution::experimental::set_value_t (int (*)()), hpx::execution::experimental::set_error_t (std::__exception_ptr::exception_ptr), hpx::execution::experimental::set_stopped_t ()>::type>::value' "mylib::receiver_1 should be a receiver of an int"
    static_assert(
    ^
/home/extended/hpx/libs/core/execution_base/tests/unit/basic_receiver.cpp:259:5: error: static_assert failed due to requirement 'is_receiver_of<mylib::receiver_3, hpx::execution::experimental::detail::compose_signatures<hpx::execution::experimental::set_value_t (int (*)()), hpx::execution::experimental::set_error_t (std::__exception_ptr::exception_ptr), hpx::execution::experimental::set_stopped_t ()>::type>::value' "mylib::receiver_3 should be a receiver of an int"
    static_assert(
    ^
/home/extended/hpx/libs/core/execution_base/tests/unit/basic_receiver.cpp:266:5: error: static_assert failed due to requirement 'is_nothrow_receiver_of<mylib::receiver_3, hpx::execution::experimental::detail::compose_signatures<hpx::execution::experimental::set_value_t (int (*)()), hpx::execution::experimental::set_error_t (std::__exception_ptr::exception_ptr), hpx::execution::experimental::set_stopped_t ()>::type>::value' "mylib::receiver_3 should be a nothrow receiver of an int"
    static_assert(
    ^
3 errors generated.