Workaround: OSError: [Errno 18] Invalid cross-device link
    
    The tests were hitting:
    
    OSError: [Errno 18] Invalid cross-device link: b'/tmp/...' -> b'/builddir/.local/share/Trash/files/...'
    
    In local mock or in Copr. It only happens in certain containerized environments.
    
    By setting TMPDIR inside the builddir, we workaround this problem.