Don't fail over empty or faulty lines

[aleixpol]

If we're not going to be able to unpack it, ignore the line.

This is what it looks like on Arch Linux. Note the empty line in the end:

$ cat /etc/os-release 
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
ID_LIKE=archlinux
ANSI_COLOR="0;36"
HOME_URL="https://www.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://bugs.archlinux.org/"

$ 

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[kalikiana]

Would you mind adding a unit test to snapcraft/tests/test_common.py with your failing os-release and one that doesn't have an empty line?

[sergiusens]

\o/

[aleixpol]

\o/