Comment 1 for bug 1825020

Are you sure this is reproducible in pure nova code? Because this looks like forked nova code for starlingx:

Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/nfv_plugins/nfvi_plugins/nfvi_compute_api.py", line 2127, in resize_instance
    future.result = (yield)

Looking at this code in the compute API in pure nova, it looks like that error only gets raised here:

https://github.com/openstack/nova/blob/e25d59078e61fe9f925dbef53dfe88e575d34dab/nova/compute/api.py#L655

Which is being called from resize now:

https://github.com/openstack/nova/blob/e25d59078e61fe9f925dbef53dfe88e575d34dab/nova/compute/api.py#L3652

As a result of this change in stein:

https://review.openstack.org/#/c/620706/

Note that root_bdm=None there so that's how we get into the else block of _validate_flavor_image_nostatus because it's not considering the instance as volume-backed.