Allow Vagrantfile to load when using --local

bin/vagrant

@@ -44,7 +44,9 @@ argv.each_index do |i|
 
     # Do not load plugins when performing plugin operations
     if arg == "plugin"
-      opts[:vagrantfile_name] = ""
+      if argv.none?{|a| a == "--local" }
+        opts[:vagrantfile_name] = ""
+      end
       ENV['VAGRANT_NO_PLUGINS'] = "1"
       # Only initialize plugins when listing installed plugins
       if argv[i+1] != "list"

test/unit/bin/vagrant_test.rb

@@ -143,5 +143,14 @@ describe "vagrant bin" do
         expect(ENV).not_to receive(:[]=).with("VAGRANT_DISABLE_PLUGIN_INIT", "1")
       end
     end
+
+    context "--local" do
+      let(:argv) { ["plugin", "install", "--local"] }
+
+      it "should not unset vagrantfile" do
+        expect(Vagrant::Environment).to receive(:new).
+          with(hash_excluding(vagrantfile_name: "")).and_return(env)
+      end
+    end
   end
 end