tests/test_cli: actually load the module from the repo
    
    We temporarily change the working directory, which means that
    'import rpmautospec' was actually loading the module from the global
    python search path. We weren't testing the code under test, but the
    installed version, and if the code wasn't installed, the test would
    fail.
    
    Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>