Merge "Replace uuid4() with uuidsentinel"

diff --cc nova/tests/unit/compute/test_compute_mgr.py
Simple merge

diff --cc nova/tests/unit/virt/libvirt/fakelibvirt.py
Simple merge

diff --cc nova/tests/unit/virt/libvirt/test_driver.py
Simple merge

diff --cc nova/tests/unit/virt/xenapi/test_vm_utils.py
Simple merge

diff --cc nova/tests/unit/virt/xenapi/test_xenapi.py
Simple merge