Ignore <internal: callers, fixes GH #50

Rakefile

@@ -15,7 +15,8 @@ end
 
 Rake::TestTask.new(:test) do |t|
   t.test_files = FileList['test/*_test.rb']
-  t.ruby_opts = ['-rubygems -I.'] if defined? Gem
+  t.ruby_opts = ['-rubygems'] if defined? Gem
+  t.ruby_opts << '-I.'
 end
 
 # Rcov ================================================================

lib/sinatra/base.rb

@@ -1049,6 +1049,7 @@ module Sinatra
         /\(.*\)/,                                        # generated code
         /rubygems\/custom_require\.rb$/,                 # rubygems require hacks
         /active_support/,                                # active_support require hacks
+        /<internal:/,                                    # internal in ruby >= 1.9.2
       ]
 
       # add rubinius (and hopefully other VM impls) ignore patterns ...