fix reference to variables

[sleep-walker]

Looks like the branch of code hasn't been updated. Leading to

 Traceback (most recent call last):
  File "/Devel/git/webmacs/webmacs/adblock.py", line 158, in _dl_ready_read
    logging.info("no need to download adblock rule: %s", url)
NameError: name 'url' is not defined. Did you mean: 'QUrl'?

and

Traceback (most recent call last):
  File "/Devel/git/webmacs/webmacs/adblock.py", line 160, in _dl_ready_read
    os.utime(path, None)
NameError: name 'path' is not defined