Ruby rescue gotcha

Today in the codebase at my day job, I found a particularly cute bug related to "rescue" in Ruby. This isn't a particularly unknown gotcha–I've read about it on the net at least once–but this is a particularly sweet (or devious) manifestation, and as far as I can tell it was purely accidental, not a contrived example.

The following example uses rspec, but the key thing is begin; 2 / 0 rescue NoMethodError; end versus begin; 2 / 0; rescue NoMethodError; end–what is the difference between these two statements?

require File.expand_path('spec_helper', File.dirname(__FILE__))

describe "enigma" do
  it "fails, but why" do
    lambda { begin; 2 / 0 rescue NoMethodError; end }.
      should raise_error(ZeroDivisionError)
  end

  it "passes, but why" do
    lambda { begin; 2 / 0; rescue NoMethodError; end }.
      should raise_error(ZeroDivisionError)
  end
end

I'll post the answer in a comment in a few days; feel free to post your answers as comments if you wish.