Manually merged from https://github.com/rubygems/rubygems/pull/2636

Enable Style/EmptyLinesAroundClassBody rubocop cop.

lib/rubygems/package.rb

@@ -47,11 +47,13 @@ require 'rubygems/user_interaction'
 require 'zlib'
 
 class Gem::Package
+
   include Gem::UserInteraction
 
   class Error < Gem::Exception; end
 
   class FormatError < Error
+
     attr_reader :path
 
     def initialize(message, source = nil)
@@ -63,13 +65,16 @@ class Gem::Package
 
       super message
     end
+
   end
 
   class PathError < Error
+
     def initialize(destination, destination_dir)
       super "installing into parent path %s of %s is not allowed" %
               [destination, destination_dir]
     end
+
   end
 
   class NonSeekableIO < Error; end
@@ -706,6 +711,7 @@ EOM
   rescue Zlib::GzipFile::Error => e
     raise Gem::Package::FormatError.new(e.message, entry.full_name)
   end
+
 end
 
 require 'rubygems/package/digest_io'