test: Parse home directory instead hardcoding
test: Parse home directory instead hardcoding

In fedora atomic changed home directory [1] and it made tests fail.
To prevent this in the future, parse home directory and validate it
exits (stat will fail if not), is owned by berta and is not just '/' but
something ending with '/berta'.

[1] https://src.fedoraproject.org/rpms/selinux-policy/pull-request/14

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