Varnish is not working as expected

[nicopace]

When you run this branch tests: https://code.launchpad.net/~nicopace/charms/trusty/varnish/all-tests
You can see that the 11-varnish-worpress test fails, due to varnish returning a different content than wordpress.

<pre>
DEBUG:runner: outcome.errors.clear()
DEBUG:runner:
DEBUG:runner:======================================================================
DEBUG:runner:ERROR: test_deployed (__main__.TestDeployment)
DEBUG:runner:----------------------------------------------------------------------
DEBUG:runner:Traceback (most recent call last):
DEBUG:runner: File "/home/ubuntu/tmp/all-tests/tests/11-varnish-wordpress", line 51, in test_deployed
DEBUG:runner: msg="Varnish is returning differnt content than wordpress.")
DEBUG:runner: File "/usr/lib/python3/dist-packages/amulet/helpers.py", line 140, in raise_status
DEBUG:runner: sys.exit(code)
DEBUG:runner:SystemExit: 1
DEBUG:runner:
DEBUG:runner:----------------------------------------------------------------------
DEBUG:runner:Ran 1 test in 170.991s
DEBUG:runner:
DEBUG:runner:FAILED (errors=1)
DEBUG:runner:Varnish is returning differnt content than wordpress.
DEBUG:runner:

DEBUG:runner:Exit Code: 1
    11-varnish-wordpress ERROR
DEBUG:bundletester.utils:Updating JUJU_ENV: "local" -> ""

------------------------------------------------------------------------------
ERROR: varnish::11-varnish-wordpress
[/home/ubuntu/tmp/all-tests/tests/11-varnish-wordpress exit 1]
</pre>