(PUP-9318) fix $LOAD_PATH handling in device

Previous to this commit, `puppet device` would use the proxy agent's
`:libdir` to load all code, since we changed the `:vardir` setting, but
not the `:libdir`. While `Puppet::Settings` has hooks to change the
`$LOAD_PATH` when `:libdir` changes, those do not trigger when the
change is effected through a interpolation, like in this case.

By setting the `:libdir` explicitely the hook is triggered, and the
`$LOAD_PATH` gets updated.

This commit also removes the `device` subcommand from the CLI's default
`$LOAD_PATH` processing.

Author: DavidS

lib/puppet/application/device.rb

@@ -1,4 +1,5 @@
 require 'puppet/application'
+require 'puppet/configurer'
 require 'puppet/util/network_device'
 
 class Puppet::Application::Device < Puppet::Application
@@ -222,6 +223,7 @@ def main
       raise _("missing argument: --target is required when using --apply") if options[:target].nil?
       raise _("%{file} does not exist, cannot apply") % { file: options[:apply] } unless File.file?(options[:apply])
     end
+    libdir = Puppet[:libdir]
     vardir = Puppet[:vardir]
     confdir = Puppet[:confdir]
     certname = Puppet[:certname]
@@ -251,9 +253,11 @@ def main
 
           # override local $vardir and $certname
           Puppet[:confdir] = ::File.join(Puppet[:devicedir], device.name)
+          Puppet[:libdir] = ::File.join(Puppet[:devicedir], device.name, 'lib')
           Puppet[:vardir] = ::File.join(Puppet[:devicedir], device.name)
           Puppet[:certname] = device.name
 
+          Puppet::Configurer::PluginHandler.new.download_plugins(env)
           # this init the device singleton, so that the facts terminus
           # and the various network_device provider can use it
           Puppet::Util::NetworkDevice.init(device)
@@ -316,6 +320,7 @@ def main
           # If we rescued an error, then we return 1 as the exit code
           1
         ensure
+          Puppet[:libdir] = libdir
           Puppet[:vardir] = vardir
           Puppet[:confdir] = confdir
           Puppet[:certname] = certname

lib/puppet/util/command_line.rb

@@ -106,7 +106,7 @@ def initialize(subcommand_name, command_line)
         def run
           # For most applications, we want to be able to load code from the modulepath,
           # such as apply, describe, resource, and faces.
-          # For agent, we only want to load pluginsync'ed code from libdir.
+          # For agent and device, we only want to load pluginsync'ed code from libdir.
           # For master, we shouldn't ever be loading per-environment code into the master's
           # ruby process, but that requires fixing (#17210, #12173, #8750). So for now
           # we try to restrict to only code that can be autoloaded from the node's
@@ -116,8 +116,7 @@ def run
           # have an appropriate application-wide current_environment set.
           # If we cannot find the configured environment, which may not exist,
           # we do not attempt to add plugin directories to the load path.
-          #
-          if @subcommand_name != 'master' and @subcommand_name != 'agent'
+          unless ['master', 'agent', 'device'].include? @subcommand_name
             if configured_environment = Puppet.lookup(:environments).get(Puppet[:environment])
               configured_environment.each_plugin_directory do |dir|
                 $LOAD_PATH << dir unless $LOAD_PATH.include?(dir)