Don't load any plugins for `vagrant plugin` [GH-1418]

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## 1.1.1 (unreleased)
 
+IMPROVEMENTS:
+
+  - Don't load plugins on any `vagrant plugin` command, so that errors
+    are avoided. [GH-1418]
+
 BUG FIXES:
 
   - Quote keys to StringBlockEditor so keys with spaces, parens, and

lib/vagrant.rb

@@ -168,6 +168,12 @@ module Vagrant
   #
   # @param [String] name Name of the plugin to load.
   def self.require_plugin(name)
+    if ENV["VAGRANT_NO_PLUGINS"]
+      logger = Log4r::Logger.new("vagrant::root")
+      logger.warn("VAGRANT_NO_PLUGINS is set, not loading 3rd party plugin: #{name}")
+      return
+    end
+
     # Redirect stdout/stderr so that we can output it in our own way.
     previous_stderr = $stderr
     previous_stdout = $stdout
@@ -212,8 +218,8 @@ module Vagrant
         :plugin => name
     end
   ensure
-    $stderr = previous_stderr
-    $stdout = previous_stdout
+    $stderr = previous_stderr if previous_stderr
+    $stdout = previous_stdout if previous_stdout
   end
 end
 

lib/vagrant/environment.rb

@@ -631,13 +631,6 @@ module Vagrant
     # Loads the Vagrant plugins by properly setting up RubyGems so that
     # our private gem repository is on the path.
     def load_plugins
-      if ENV["VAGRANT_NO_PLUGINS"]
-        # If this key exists, then we don't load any plugins. It is a "safe
-        # mode" of sorts.
-        @logger.warn("VAGRANT_NO_PLUGINS is set. Not loading 3rd party plugins.")
-        return
-      end
-
       # Add our private gem path to the gem path and reset the paths
       # that Rubygems knows about.
       ENV["GEM_PATH"] = "#{@gems_path}#{::File::PATH_SEPARATOR}#{ENV["GEM_PATH"]}"