Comment 1 for bug 1687921

Hi, I have tested it.

The patch that I have submited is in the situation when doing backup of volume or snapshot launched nova instance.

The error above occurred when doing backup of nova instance which was launched by image, cause it has no info about 'block_device_mapping', I think I should add the "none judgment" before line 205 of nova.py.

Few days ago, with more in-depth testing, I found that freezer does not support volume or snapshot correctly and the patch I have submited will fail when doing backup of image launched nova instance. So I submit a new patch https://review.openstack.org/#/c/460427/ and fix the error(include the above error).

The above error will not occur when doing backup of volume or snapshot based nova instance.