Issue #11747: Fix range formatting in context and unified diffs.

diff --cc Misc/NEWS
index d02a22ebb8eda25537af6ae046a8cc1cd68e2bf4,02f75d4a8c98c11918501cc152be2399c8991c4f..34369cf8d9fb212cbc5683b12c0d717b6a44a93d
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -103,12 -53,11 +103,15 @@@ Core and Builtin
  Library
  -------
  
 +- logging.basicConfig now supports an optional 'handlers' argument taking an
 +  iterable of handlers to be added to the root logger. Additional parameter
 +  checks were also added to basicConfig.
 +
  - Issue #11814: Fix likely typo in multiprocessing.Pool._terminate().
  
+ - Issue #11747: Fix range formatting in difflib.context_diff() and
+   difflib.unified_diff().
+ 
  - Issue #8428: Fix a race condition in multiprocessing.Pool when terminating
    worker processes: new processes would be spawned while the pool is being
    shut down.  Patch by Charles-François Natali.