Update yaml-cpp-config.cmake.in

Author: Levi-Armstrong

yaml-cpp-config.cmake.in

@@ -19,15 +19,15 @@ include("${CMAKE_CURRENT_LIST_DIR}/yaml-cpp-targets.cmake")
 # These are IMPORTED targets created by yaml-cpp-targets.cmake
 set(YAML_CPP_LIBRARIES "@EXPORT_TARGETS@")
 
+# Protect against multiple inclusion, which would fail when already imported targets are added once more.
 if(NOT TARGET yaml-cpp)
   add_library(yaml-cpp INTERFACE IMPORTED) 
   target_link_libraries(yaml-cpp INTERFACE yaml-cpp::yaml-cpp) 
-endif()
-
-if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.17)
-  set_target_properties(yaml-cpp PROPERTIES 
-    DEPRECATION "The target yaml-cpp is deprecated and will be removed in version 0.10.0. Use the yaml-cpp::yaml-cpp target instead."
-  )
+  if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.17)
+    set_target_properties(yaml-cpp PROPERTIES 
+      DEPRECATION "The target yaml-cpp is deprecated and will be removed in version 0.10.0. Use the yaml-cpp::yaml-cpp target instead."
+    )
+  endif()
 endif()
 
 check_required_components(yaml-cpp)