Struct.new block and constancts

gistfile1.rb

1.8.7 :001 > Foo = Struct.new(:id) do
1.8.7 :002 >     BAR = 5
1.8.7 :003?>   end
 => Foo 
1.8.7 :004 > BAR
 => 5 
1.8.7 :005 > Foo::BAR
(irb):5: warning: toplevel constant BAR referenced by Foo::BAR
 => 5 

1.9.3p194 :001 > Foo = Struct.new(:id) do
1.9.3p194 :002 >     BAR = 5
1.9.3p194 :003?>   end
 => Foo 
1.9.3p194 :004 > BAR
 => 5 
1.9.3p194 :005 > Foo::BAR
(irb):5: warning: toplevel constant BAR referenced by Foo::BAR
 => 5