Followup to #7502: add __hash__ method and tests.

diff --cc Lib/doctest.py
index 5d315cc5a3e58ab812ae7783d8b51ca99ba03395,234733e5651c5359d2aee3704b6bd7494c76f54f..aba98dc5a3548926cf8a4962c9e4dbd92e6dda0b
--- 1/Lib/doctest.py
--- 2/Lib/doctest.py
+++ b/Lib/doctest.py
@@@ -454,7 -454,11 +454,10 @@@ class Example
      def __ne__(self, other):
          return not self == other
  
+     def __hash__(self):
+         return hash((self.source, self.want, self.lineno, self.indent,
+                      self.exc_msg))
  
 -
  class DocTest:
      """
      A collection of doctest examples that should be run in a single

diff --cc Lib/test/test_doctest.py
Simple merge