I am realizing that many people like to use find_library() as a way of converting a portable name like “magic” (from building with -lmagic) into a platform-specific name (libmagic.so.1, libmagic.dylib, magic.dll, etc), and then pass this to LoadLibrary() or equivalent. So searching Python’s runpath would probably be valid for that use case.

IMO the extra searching is inefficient, and not robust if there is more than one version of the library. Personally I would be more interested in adding an alternative function, maybe make_library_name("magic", "1") -> "libmagic.so.1", or cdll.LoadLibraryByPortableName("magic", "1").