Merge fix-mountinfo-tests-in-container [f=] [r=danilo,adam-collard,landscape-builder] [a=Alberto Donato]
Fix the following MountInfo unittests that fail in containers (LXC and LXD) because of lack of isolation from the system:
landscape.monitor.tests.test_mountinfo.MountInfoTest.test_read_proc_mounts
landscape.monitor.tests.test_mountinfo.MountInfoTest.test_call_on_accepted