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Hi, stackers,
	I have a question to followed code in nova/tests/virt/libvirt/test_libvirt.py. My question is, when will the 'import libvirt' success and the fake libvirt not used?

try:
    import libvirt
except ImportError:
    import nova.tests.virt.libvirt.fakelibvirt as libvirt
libvirt_driver.libvirt = libvirt

Thanks
--jyh