core: Ui::Prefixed can take prefix_spaces option

lib/vagrant/ui.rb

@@ -267,7 +267,7 @@ module Vagrant
         if !opts.has_key?(:prefix) || opts[:prefix]
           prefix = OUTPUT_PREFIX
           prefix = " " * OUTPUT_PREFIX.length if \
-            type == :detail || type == :ask
+            type == :detail || type == :ask || opts[:prefix_spaces]
         end
 
         # Fast-path if there is no prefix

test/unit/vagrant/ui_test.rb

@@ -293,6 +293,11 @@ describe Vagrant::UI::Prefixed do
       subject.output("foo")
     end
 
+    it "prefixes with spaces if requested" do
+      ui.should_receive(:output).with("    #{prefix}: foo", anything)
+      subject.output("foo", prefix_spaces: true)
+    end
+
     it "prefixes every line" do
       ui.should_receive(:output).with("==> #{prefix}: foo\n==> #{prefix}: bar", anything)
       subject.output("foo\nbar")