BUG: add debugging into to check out a problem

Tests/ExternalOBJ/CMakeLists.txt

@@ -44,6 +44,8 @@ ENDIF(EXTERNAL_OBJECT)
 # Test creation of external objects by custom commands.
 SET(CUSTOM_OBJECT
   ${CMAKE_CURRENT_BINARY_DIR}/custom_object${CMAKE_C_OUTPUT_EXTENSION})
+MESSAGE("Debugging info: "
+  "${CMAKE_COMMAND} -E copy ${EXTERNAL_OBJECT} ${CUSTOM_OBJECT}")
 ADD_CUSTOM_COMMAND(
   OUTPUT ${CUSTOM_OBJECT}
   COMMAND ${CMAKE_COMMAND} -E copy ${EXTERNAL_OBJECT} ${CUSTOM_OBJECT}