jruby-1.7.6 [ x86_64 ](using rvm)

a=[1,2,3,4]
a.delete_if { |e| puts a.size; e % 2 == 0 }

4
4
4
4
=> [1, 3]

End result ok - array elements were deleted, but size was not updated during delete_if iterations and it should be.
If I run this in ruby-1.9.3-p484 [ x86_64 ]:
4
4
3
3
=> [1, 3]