Make ExceptionPresenter#fully_formatted support a nil arg.

This is necessary for cases where the error is not part
of a numbered sequence (such as a :suite hook error).

Author: myronmarston

lib/rspec/core/formatters/exception_presenter.rb

@@ -122,7 +122,8 @@ def encoded_string(string)
         end
 
         def indent_lines(lines, failure_number)
-          alignment_basis = "#{' ' * @indentation}#{failure_number}) "
+          alignment_basis = ' ' * @indentation
+          alignment_basis <<  "#{failure_number}) " if failure_number
           indentation = ' ' * alignment_basis.length
 
           lines.each_with_index.map do |line, index|

spec/rspec/core/formatters/exception_presenter_spec.rb

@@ -51,6 +51,18 @@ module RSpec::Core
         EOS
       end
 
+      it "prints no identifier when no number argument is given" do
+        expect(presenter.fully_formatted(nil)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+          |
+          |  Example
+          |  Failure/Error: # The failure happened here!#{ encoding_check }
+          |
+          |    Boom
+          |    Bam
+          |  # ./spec/rspec/core/formatters/exception_presenter_spec.rb:#{line_num}
+        EOS
+      end
+
       it "allows the caller to specify additional indentation" do
         the_presenter = Formatters::ExceptionPresenter.new(exception, example, :indentation => 4)