This requires HEAT_CREATE_TEST_IMAGE to be set for any images
to be created.
If the file (files/fedora-vm-heat-cfntools-tempest.qcow2) already
exists then disk-image-create will not be called, and the existing
image file will be registered with glance. This is most likely to
happen in the following scenarios:
- a second run of stack.sh
- the image has been pre-built elsewhere (such as during devstack-gate
image building)
Change-Id: I276573a20927e72f2cb68784f655c1ba1913ae8a
d5cccad2f0