Remove method == from Redis::Future

This helps to have a more consistent errors when operating with
Redis::Future inside a pipelined block

lib/redis/pipeline.rb

@@ -132,6 +132,9 @@ class Future < BasicObject
 
     attr_reader :timeout
 
+    # Avoid allowing people to use == inside a pipelined
+    undef :==
+
     def initialize(command, transformation, timeout)
       @command = command
       @transformation = transformation
@@ -161,6 +164,7 @@ def is_a?(other)
       self.class.ancestors.include?(other)
     end
 
+
     def class
       Future
     end

test/pipelining_commands_test.rb

@@ -126,6 +126,14 @@ def test_futures_raise_when_trying_to_access_their_values_too_early
     end
   end
 
+  def test_futures_raise_when_trying_to_compare_their_value_too_early
+    r.pipelined do
+      assert_raises(NoMethodError) do
+        r.sadd("foo", 1) == 1
+      end
+    end
+  end
+
   def test_futures_raise_when_command_errors_and_needs_transformation
     assert_raises(Redis::CommandError) do
       r.pipelined do