Tests: Fake home directory even if not set
In some cases ENV{HOME}
might not be set, e.g. when run through a systemd
service without User set.
We should still to fake HOME in such cases as some tests (e.g. FindPackageTest)
rely on it. We need only avoid setting ENV{CTEST_REAL_HOME}
in such cases. Its
possible absence seems to already be handled by tests.