[bug] can't rm image without tag

[Letty5411]

Ⅰ. Issue Description

Must add tag when run pouch rmi. I may expect pouchd to add default tag : latest.

Ⅱ. Describe what happened

14dd0653a83c   registry.hub.docker.com/library/hello-world:latest   5.95 KB

[root@rsec10229.et2sqa /home/letty.ll/pouchtest/testcases/api_cli]
#pouch rmi hello-world
Error: failed to remove image: {"message":"failed to remove image: image \"\": not found"}

#pouch rmi hello-world:latest
hello-world:latest

Ⅲ. Describe what you expected to happen

Ⅳ. How to reproduce it (as minimally and precisely as possible)

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• pouch version (use pouch version):
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others: