Conflict, cannot delete because XXX is held by an ongoing pull or build

root@vultr:~# docker rmi 3f8d2e13b904
Error response from daemon: Conflict, cannot delete because 3f8d2e13b904 is held by an ongoing pull or build
Error: failed to remove images: [3f8d2e13b904]

What should I do ? How I can debug this issue ?

root@vultr:~# docker info
Containers: 6
Images: 87
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 99
 Dirperm1 Supported: true
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.19.0-25-generic
Operating System: Ubuntu 14.04.2 LTS
CPUs: 1
Total Memory: 993.2 MiB
Name: vultr.guest
ID: SD5L:3ULB:3FUC:DOII:EY4Q:NQRS:6DOA:7OOI:2VQK:AWYW:Z7KK:24U7
WARNING: No swap limit support
root@vultr:~# docker version
Client:
 Version:      1.8.1
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   d12ea79
 Built:        Thu Aug 13 02:35:49 UTC 2015
 OS/Arch:      linux/amd64

Server:
 Version:      1.8.1
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   d12ea79
 Built:        Thu Aug 13 02:35:49 UTC 2015
 OS/Arch:      linux/amd64

systemctl restart docker
docker rmi 3f8d2e13b904