Add support for negative indices in UserString.MutableString.__setitem__
and UserString.MutableString.__delitem__.
diff --git a/Misc/NEWS b/Misc/NEWS
index a5ab25a..71e7b82 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -152,6 +152,9 @@
 - The reconvert.quote function can now emit triple-quoted strings.  The
   reconvert module now has some simple documentation.
 
+- ``UserString.MutableString`` now supports negative indices in
+  ``__setitem__`` and ``__delitem__``
+
 Build
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