unable to install vagrant plugins

[Quanah]

Currently on Ubuntu 16.04 LTS, it is impossible to install any vagrant plugins. I do /not/ have this problem using Vagrant provided by the vagrant project, only the Ub16 package:

root@ub16:~# vagrant plugin install vagrant-cachier
Installing the 'vagrant-cachier' plugin. This can take a few minutes...
/usr/lib/ruby/2.3.0/rubygems/specification.rb:946:in `all=': undefined method `group_by' for nil:NilClass (NoMethodError)
        from /usr/lib/ruby/vendor_ruby/vagrant/bundler.rb:275:in `with_isolated_gem'
        from /usr/lib/ruby/vendor_ruby/vagrant/bundler.rb:231:in `internal_install'
        from /usr/lib/ruby/vendor_ruby/vagrant/bundler.rb:102:in `install'
        from /usr/lib/ruby/vendor_ruby/vagrant/plugin/manager.rb:62:in `block in install_plugin'
        from /usr/lib/ruby/vendor_ruby/vagrant/plugin/manager.rb:72:in `install_plugin'
        from /usr/share/vagrant/plugins/commands/plugin/action/install_gem.rb:37:in `call'
        from /usr/lib/ruby/vendor_ruby/vagrant/action/warden.rb:34:in `call'
        from /usr/lib/ruby/vendor_ruby/vagrant/action/builder.rb:116:in `call'
        from /usr/lib/ruby/vendor_ruby/vagrant/action/runner.rb:66:in `block in run'
        from /usr/lib/ruby/vendor_ruby/vagrant/util/busy.rb:19:in `busy'
        from /usr/lib/ruby/vendor_ruby/vagrant/action/runner.rb:66:in `run'
        from /usr/share/vagrant/plugins/commands/plugin/command/base.rb:14:in `action'
        from /usr/share/vagrant/plugins/commands/plugin/command/install.rb:32:in `block in execute'
        from /usr/share/vagrant/plugins/commands/plugin/command/install.rb:31:in `each'
        from /usr/share/vagrant/plugins/commands/plugin/command/install.rb:31:in `execute'
        from /usr/share/vagrant/plugins/commands/plugin/command/root.rb:56:in `execute'
        from /usr/lib/ruby/vendor_ruby/vagrant/cli.rb:42:in `execute'
        from /usr/lib/ruby/vendor_ruby/vagrant/environment.rb:268:in `cli'
        from /usr/bin/vagrant:173:in `<main>'

root@ub16:~# dpkg -l vagrant
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=========================================-=========================-=========================-=======================================================================================
ii vagrant 1.8.1+dfsg-1 all Tool for building and distributing virtualized development environments

[Quanah (quanah-zimbra)]

By comparison, here is installing plugins using the build distributed by Hashicorp:

root@ub16:~# wget https://releases.hashicorp.com/vagrant/1.8.1/vagrant_1.8.1_x86_64.deb
--2016-05-07 09:35:16-- https://releases.hashicorp.com/vagrant/1.8.1/vagrant_1.8.1_x86_64.deb
Resolving releases.hashicorp.com (releases.hashicorp.com)... 23.235.39.69
Connecting to releases.hashicorp.com (releases.hashicorp.com)|23.235.39.69|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 75496368 (72M) [application/x-debian-package]
Saving to: ‘vagrant_1.8.1_x86_64.deb’

vagrant_1.8.1_x86_64.deb 100%[====================================================================================================>] 72.00M 12.8MB/s in 6.2s

2016-05-07 09:35:22 (11.6 MB/s) - ‘vagrant_1.8.1_x86_64.deb’ saved [75496368/75496368]

root@ub16:~# dpkg -i vagrant_1.8.1_x86_64.deb
Selecting previously unselected package vagrant.
(Reading database ... 99729 files and directories currently installed.)
Preparing to unpack vagrant_1.8.1_x86_64.deb ...
Unpacking vagrant (1:1.8.1) ...

Setting up vagrant (1:1.8.1) ...
root@ub16:~#
root@ub16:~#
root@ub16:~#
root@ub16:~# vagrant plugin install vagrant-timezone vagrant-cachier
Installing the 'vagrant-timezone' plugin. This can take a few minutes...
Installed the plugin 'vagrant-timezone (1.1.0)'!
Installing the 'vagrant-cachier' plugin. This can take a few minutes...
Installed the plugin 'vagrant-cachier (1.2.1)'!