Fixes #7344 - ignore saving errors during fact parsing

@GregSutcliffe and @ohadlevy, could you please test the patch on affected machines? I was not able to reproduce some of your issues.
I think this test should have three interfaces. The bug is really that the import halts when an error is encountered, instead of skipping on to the next interface. So the test should be

eth0: primary
eth1: same ip as eth0
eth2: never-seen-before interface with new ip

Then we can test that host.interfaces increases by one (from eth2) despite eth1 failing.