[Merge] lp:~sjakthol/software-properties/fix-1111291 into lp:software-properties

[Sami Jaktholm]

The related bug report shows that the fallback code is activated due to invalid response (http.client.BadStatusLine: ''). Looking at the urrlib.request code around the exception it only seems to convert socket.error to URLError but exceptions from httplib propagate all the way back to clients. These exceptions then trigger the pycurl code that fails in python3.

But anyways, I'll change this to fit your suggestion (it's way cleaner than the current try/except mess).
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https://code.launchpad.net/~sjakthol/software-properties/fix-1111291/+merge/157514
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~sjakthol/software-properties/fix-1111291 into lp:software-properties.