So, Martin, are you then arguing that this should in fact be considered a bug in ZipFile?  The documentation for the constructor says "Open a ZIP file, where file can be either a path to a file (a string) or a file-like object."  Reading that I would certainly expect it to accept a relative path, and for that path to be relative to the CWD at the time I called ZipFile, not at the time I called extractall.