zcf resulting in "inappropriate ioctl for device"

[piejanssens]

zsh> cf install-plugin -r CF-Community "html5-plugin"

Searching CF-Community for plugin html5-plugin...
Plugin html5-plugin 1.4.6 found in: CF-Community
Plugin html5-plugin 1.4.4 is already installed.
                                               Attention: Plugins are binaries written by potentially untrusted authors.
                                                                                                                       Install and use plugins at your own risk.
inappropriate ioctl for device
FAILED

It's not just zsh:

zsh> bash
pieter@BE-PF24QJFD:~$ cd .zsh_functions/
pieter@BE-PF24QJFD:~/.zsh_functions$ ./zcf install-plugin html5-plugin
Searching CF-Community for plugin html5-plugin...
Plugin html5-plugin 1.4.6 found in: CF-Community
Plugin html5-plugin 1.4.6 is already installed.
Attention: Plugins are binaries written by potentially untrusted authors.
Install and use plugins at your own risk.
inappropriate ioctl for device
FAILED