guzzle/guzzle — pull request #546 by unixo (2014-01-31 13:33:29+00:00)
Title: Remove cookie with empty value

Scenario:
- the server tries to re-set a cookie with an empty value (`Cookie:isValid` would return `false` for it)
- the jar already contains a valid cookie with the same name

The cookie must be deleted and not used anymore in next requests.