Don't slugify() None names (Docker images may have empty names)

[Roman Rader]

Commit 77a9574238d416b59b7d38ca69fc7ca22c1479b6 broke docker virt. in Nova - I can't retrieve list of images

$ nova image-list
ERROR: <type 'NoneType'> can't be decoded

It's related to https://bugs.launchpad.net/ubuntu/+source/python-novaclient/+bug/1266118 I suppose

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Chris Buccella (chris-buccella)]

Probably not a duplicate of 1266118; that just changed slugify() to to_slug(). The problem likely existed before the change as well.

[Roman Rader (rrader)]

It's not duplicate, this bug appeared after fixing that )
Previously all worked

[Paul Czarkowski (paulcz)]

I get the same( similar? ) except when I run nova boot.

```
vagrant@devstack:~$ nova image-list
+--------------------------------------+---------------------------------+--------+--------+
| ID | Name | Status | Server |
+--------------------------------------+---------------------------------+--------+--------+
| 1c1959aa-971a-4445-91a4-72c5191ca5ca | - | ACTIVE | |
| 20a8adb2-3965-4f73-ad22-68da47640fb7 | - | ACTIVE | |
| 273186ed-5628-40b3-8f76-227a5bab12ae | - | ACTIVE | |
| 2793b46f-1d92-4ad5-95b6-f63fea96a459 | - | ACTIVE | |
| 28e98e0c-8eca-4ccf-a813-50fdca85927b | - | ACTIVE | |
| 30b89709-a8a9-4190-8ce3-733833a6d531 | - | ACTIVE | |
| 44c05ee6-d1f9-4f43-9b5d-1be47b239c83 | - | ACTIVE | |
| 6f36f6ed-bf8c-401e-b5c1-e094ffd7f913 | - | ACTIVE | |
| 7224a860-bd6f-4ce8-8fea-c77f03d1a914 | - | ACTIVE | |
| 78b65457-20cd-4ead-bac4-748dde93223d | - | ACTIVE | |
| 796f2473-fc0e-4120-9201-dfae94c4bce9 | - | ACTIVE | |
| 904d8f79-94c5-4ba9-85cc-0fc739d9aa0a | - | ACTIVE | |
| 9e6f7450-2dd6-4afd-b815-96038e9e734c | - | ACTIVE | |
| a72f8503-0537-4fb7-bf38-7b2d7d9ba843 | - | ACTIVE | |
| d4dbbdd9-637f-42e4-aae0-d636c1c28c49 | - | ACTIVE | |
| 0cee3dc1-225a-45e4-abbf-c3965c97962b | cirros-0.3.1-x86_64-uec | ACTIVE | |
| bc037a4f-c0f8-4c0b-944e-9602b792841a | cirros-0.3.1-x86_64-uec-kernel | ACTIVE | |
| 4765155f-b0c7-4fe6-b9a6-afa873ebb399 | cirros-0.3.1-x86_64-uec-ramdisk | ACTIVE | |
| 5cc41ea7-9fb9-406b-8b48-b8755a86fc1f | docker-busybox:latest | ACTIVE | |
| 97161f25-4da3-4fe0-8109-5e01ce71aed7 | nodejs:latest | ACTIVE | |
+--------------------------------------+---------------------------------+--------+--------+
vagrant@devstack:~$ nova boot --flavor 1 --image docker-busybox:latest dummy
ERROR: <type 'NoneType'> can't be decoded
```

[Chris Buccella (chris-buccella)]

Change merged: https://review.openstack.org/#/c/65665/