Bug 1289792

*Description of problem:

Docker always adds a `/``in front of the tag names (after adding new tags):

```
REPOSITORY                              TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
/image                                  latest              38ffe511a292        8 minutes ago       271.5 MB
```

*Version-Release number of selected component (if applicable):

```
Client:
 Version:         1.9.1-fc23
 API version:     1.21
 Package version: docker-1.9.1-2.git78bc3ea.fc23.x86_64
 Go version:      go1.5.1
 Git commit:      f7c1d52-dirty
 Built:           Fri Nov 20 21:07:14 UTC 2015
 OS/Arch:         linux/amd64

Server:
 Version:         1.9.1-fc23
 API version:     1.21
 Package version: docker-1.9.1-2.git78bc3ea.fc23.x86_64
 Go version:      go1.5.1
 Git commit:      f7c1d52-dirty
 Built:           Fri Nov 20 21:07:14 UTC 2015
 OS/Arch:         linux/amd64
```

*How reproducible:

Every time


*Steps to Reproduce:

1. Run `docker build -t test .` with a Dockerfile like this: `FROM ubuntu:14.04`
2. Run `docker images`
3. Run `docker build -t foo .` with a Dockerfile like this: `FROM test`
4. Run `docker images`
5. Run `docker rmi /test`
6. Run `docker rmi test foo`

*Actual results:

1. works, but:
2. you can see `/test`
3. works, it takes `/test` or `test`
4. you can see `/test` and `/foo`
5. failes with message:
```
EOF
Error: failed to remove images: [/test]
```

6 . works and removes both images and neither `test` nor `/test` is visible...

*Expected results:

2. image should be named `test`
4. image should be named `foo`

*Additional info:


 I think since I have upgraded from `docker.x86_64 1:1.8.2-14.git8f9eabc.fc23` -> `docker.x86_64 1:1.9.1-2.git78bc3ea.fc23`

See https://github.com/docker/docker/issues/18406

*docker info:
```
Containers: 2
Images: 181
Server Version: 1.9.1-fc23
Storage Driver: devicemapper
 Pool Name: docker-253:2-5770-pool
 Pool Blocksize: 65.54 kB
 Base Device Size: 107.4 GB
 Backing Filesystem: 
 Data file: /dev/loop0
 Metadata file: /dev/loop1
 Data Space Used: 9.917 GB
 Data Space Total: 107.4 GB
 Data Space Available: 17.2 GB
 Metadata Space Used: 13.64 MB
 Metadata Space Total: 2.147 GB
 Metadata Space Available: 2.134 GB
 Udev Sync Supported: true
 Deferred Removal Enabled: false
 Deferred Deletion Enabled: false
 Deferred Deleted Device Count: 0
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Library Version: 1.02.109 (2015-09-22)
Execution Driver: native-0.2
Logging Driver: journald
Kernel Version: 4.2.6-301.fc23.x86_64
Operating System: Fedora 23 (Twenty Three)
CPUs: 4
Total Memory: 7.682 GiB
```