Mycroft-core: Package python-virtualenv is not available

On clean install of Ubuntu 17.10:

osboxes@osboxes:~$ git clone https://github.com/MycroftAI/mycroft-core.git
Cloning into 'mycroft-core'...
remote: Counting objects: 9309, done.
remote: Total 9309 (delta 0), reused 0 (delta 0), pack-reused 9309
Receiving objects: 100% (9309/9309), 82.34 MiB | 7.80 MiB/s, done.
Resolving deltas: 100% (5591/5591), done.
osboxes@osboxes:~$ cd mycroft-core
osboxes@osboxes:~/mycroft-core$ ./build_host_setup_debian.sh
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package python-virtualenv is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'python-virtualenv' has no installation candidate
E: Unable to locate package virtualenvwrapper
E: Unable to locate package swig
E: Unable to locate package s3cmd
E: Unable to locate package portaudio19-dev
E: Unable to locate package mpg123
E: Unable to locate package flac
E: Unable to locate package libfann-dev