return False when the event was set and cleared right after.

On platforms that do not support (symbolic) links, tarfile offers a
work-around and extracts a link in an archive as the regular file the link is
pointing to. On other platforms, this code was accidentally executed even
after the link had been successfully extracted which failed due to the already
existing link.

(except when SSLv2 is explicitly asked for).

Vilmos Nebehaj.

use list() to wrap range() in itertools.permutations() example; thanks to Romain MORLEVAT from docs@