More formally: it's unspecified. I'd like to propose this general principle: If you pass a relative path to some library that gets stored in the library, it's unspecified whether the cwd is consider at the point of passing the path or at the point of using it in some operation.

Applications that want to be cwd-agnostic must always use abspath.

The only exceptions are operations where there is some explicit open() operation that is documented to interpret the path name; for these, it is clear that the cwd is considered inside the open().