Does not catch problematic certificate chains

[fuglede]

This one is inspired by EFForg/https-everywhere#4280 (comment) and EFForg/https-everywhere#2585 I figured I'd try to run the checker against a ruleset which would cause problems in the wild, and which I would have expected to be caught by the checker. Rulesets with targets serving broken chains show up in pull requests every now and then, so certainly it would be nice if the existing test framework would catch those, but unfortunately it seems that it does not.

Steps to reproduce:

• Run the checker on a ruleset with target hosts serving bad chains (such as this one).

Expected results:

• An output of the form ERROR rules/Drugcom.de.xml: Fetch error: http://www.drugcom.de/ => https://www.drugcom.de/: (6, 'SSL certificate problem: unable to get local issuer certificate')

Actual results:

• Test passes