update-symbols-ppa doesn't end nice if they are missing builds

[Jose Manuel Santamaria Lema]

If you are trying to update the symbols files an some logs aren't available yet because the package in question isn't built yet for all the architectures, this is what happens:

user@host:~/kubuntu-dev/applications-17.04.1/akonadi$ update-symbols-ppa -d artful
Source package: akonadi
Source package version: 4:17.04.1
Temporary download directory: /tmp/tmp_stodf5g
Downloading: https://launchpad.net/~kubuntu-ppa/+archive/ubuntu/staging-kdeapplications/+build/12562543/+files/buildlog_ubuntu-artful-amd64.akonadi_4%3A17.04.1-0ubuntu1~ubuntu17.10~ppa3_BUILDING.txt.gz
Downloading: None
Error getting the package logs from Launchpad
Invalid URL 'None': No schema supplied. Perhaps you meant http://None?