OSError when the cookie jar gets cleared

[JustAnotherArchivist]

While attempting to work around Python's cookie jar's poor performance on large, long-running jobs that span many hosts (cf. #448), I attempted to call the http.cookiejar.CookieJar.clear method. I tried this twice and it resulted in these OSError crashes: [Errno 9] Bad file descriptor and [Errno 29] Illegal seek. (wpull suppressed the traceback.) I did not investigate further why this happened, why the errors were different despite applying the same commands, or what went wrong really.

ArchiveTeam/ArchiveBot#503