Fix raising command error for first command in pipeline (#788)

Also, remove a workaround that was added for a subset of commands.

Author: dylanahsmith

lib/redis.rb

@@ -2936,12 +2936,8 @@ def method_missing(command, *args)
 
   FloatifyPairs =
     lambda { |result|
-      if result.respond_to?(:each_slice)
-        result.each_slice(2).map do |member, score|
-          [member, Floatify.call(score)]
-        end
-      else
-        result
+      result.each_slice(2).map do |member, score|
+        [member, Floatify.call(score)]
       end
     }
 

lib/redis/client.rb

@@ -191,13 +191,10 @@ def call_pipelined(commands)
         exception = nil
 
         process(commands) do
-          result[0] = read
-
-          @reconnect = false
-
-          (commands.size - 1).times do |i|
+          commands.size.times do |i|
             reply = read
-            result[i + 1] = reply
+            result[i] = reply
+            @reconnect = false
             exception = reply if exception.nil? && reply.is_a?(CommandError)
           end
         end