Forward-port fix for OS X and VirtualBox bug from 1-0-stable

plugins/providers/virtualbox/driver/base.rb

@@ -317,9 +317,24 @@ module VagrantPlugins
           # Append in the options for subprocess
           command << { :notify => [:stdout, :stderr] }
 
+          # The following is a workaround for a combined VirtualBox and
+          # Mac OS X 10.8 bug:
+          #
+          # Remove the DYLD_LIBRARY_PATH environmental variable on Mac. This
+          # is to fix a bug in Mac OS X 10.8 where a warning is printed to the
+          # console if this is set when executing certain programs, which
+          # can cause some VBoxManage commands to break because they work
+          # by just reading stdout and don't expect the OS to just inject
+          # garbage into it.
+          old_dyld_lib_path = ENV.delete("DYLD_LIBRARY_PATH")
+
           Vagrant::Util::Busy.busy(int_callback) do
             Vagrant::Util::Subprocess.execute(@vboxmanage_path, *command, &block)
           end
+        ensure
+          # Reset the library path if it was set before. See above comments
+          # for more information on why this was unset in the first place.
+          ENV["DYLD_LIBRARY_PATH"] = old_dyld_lib_path if old_dyld_lib_path
         end
       end
     end