Code like the following breaks font-locking logic of ruby-mode:

expected_source = <<-END.strip_indent
              each do |x|
                some_method
                other_method
              end
            END


The second END gets highlighted as a constant, instead of a string. I guess the two consecutive ends cause the problem.

Here's a screenshot - http://i42.tinypic.com/122jeap.jpg

In GNU Emacs 24.3.1 (x86_64-apple-darwin12.4.0, NS apple-appkit-1187.39)
 of 2013-08-12 on Bozhidars-MacBook-Pro.local
Windowing system distributor `Apple', version 10.3.1187
Configured using:
 `configure '--prefix=/usr/local/Cellar/emacs/24.3' '--without-dbus'
 '--enable-locallisppath=/usr/local/share/emacs/site-lisp'
 '--infodir=/usr/local/Cellar/emacs/24.3/share/info/emacs'
 '--without-gnutls' '--with-ns' '--disable-ns-self-contained' 'CC=cc''



-- 
Cheers,
Bozhidar