merged branch jfsimon/issue-3896 (PR #4001)
merged branch jfsimon/issue-3896 (PR #4001)

Commits
-------

cd783fb [HttpKernel] Fixed cache vary lookup (fixes #3896).

Discussion
----------

[HttpKernel] Fixed cache vary lookup (fixes #3896).

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: #3896

symfony/http-kernel,symfony/HttpKernel