Don't handle encoding with Ruby 1.8.7

We are following the same behavior as for rspec-support
https://github.com/rspec/rspec-support/blob/9940a8656071655b807f772f36101b4d27f1b67d/lib/rspec/support/spec/string_matcher.rb#L8

Author: benoittgt

lib/rspec/core/formatters/exception_presenter.rb

@@ -246,7 +246,12 @@ def formatted_message_and_backtrace(colorizer)
 
         def encoded_description(description)
           return if description.nil?
-          encoded_string(description)
+
+          if String.method_defined?(:encoding)
+            encoded_string(description)
+          else # for 1.8.7
+            description
+          end
         end
 
         def exception_backtrace

spec/rspec/core/formatters/exception_presenter_spec.rb

@@ -94,19 +94,21 @@ module RSpec::Core
         EOS
       end
 
-      it 'allows the caller to add encoded description' do
-        the_presenter = Formatters::ExceptionPresenter.new(exception, example,
-                                                           :description => "ジ".encode("CP932"))
+      if String.method_defined?(:encoding)
+        it 'allows the caller to add encoded description' do
+          the_presenter = Formatters::ExceptionPresenter.new(exception, example,
+                                                             :description => "ジ".encode("CP932"))
 
-        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+          expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |  1) ジ
           |     Failure/Error: # The failure happened here!#{ encoding_check }
           |
           |       Boom
           |       Bam
           |     # ./spec/rspec/core/formatters/exception_presenter_spec.rb:#{line_num}
-        EOS
+          EOS
+        end
       end
 
       it 'allows the caller to omit the description' do