Some cookies trigger this cookielib bug.

The bug is analogous to...

if a == ...:
    new_a = a + other_value

if new_a ... :
    foo()

But, "new_a" doesn't exist if the first condition
fails.  I included a lot of lines of context to show
that it's correct without having to see surrounding code.

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Applied to Lib/cookielib.py 1.5 and 1.4.2.1

Thanks for the patch.

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Well spotted, Chad.  However, I am unable to see how this
bug ever causes an exception in practice: witness
test_cookielib.CookieTests.test_domain_return_ok().

The reason is that neither the request-host nor the
effective request-host ever start with a dot (and it
wouldn't matter if they did, for the purposes of this
method), so the code should be simplified as per patch 1117114.

Clearly, "Some cookies trigger this cookielib bug." implies
my reasoning above is incorrect.  Chad, did you really find
a cookie that triggers this, or do you just have a sharp
eye?  If the former, I'd be very pleased to see a test case
that triggers the bug (even if you can't provide running code).

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Yes, jjlee, I found this bug through experiment, not reading
code.  Specifically, a program I'm writing to interface to
Netflix' terrible queue interface discovered it.

I can provide you, jjlee, source code that excercises it, in
a week or so, after the code stabilizes again.  Should I
send it to you then?

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Please do.  Thanks.

Looking again, I guess the problem must be that you have a
relative URL but no Host header (so the erhn is just
".local"), which I guess reveals another problem in
somebody's code.