Issue #6093: Fix off-by-one error in locale.strxfrm.

Misc/NEWS

@@ -54,6 +54,11 @@ Library
   now it does.  This also means getfp method now returns the real fp.
 
 
+Extension Modules
+-----------------
+
+- Issue #6093: Fix off-by-one error in locale.strxfrm.
+
 Tests
 -----
 

Modules/_localemodule.c

@@ -314,7 +314,7 @@ PyLocale_strxfrm(PyObject* self, PyObject* args)
             PyErr_NoMemory();
             goto exit;
         }
-        n2 = wcsxfrm(buf, s, n2);
+        n2 = wcsxfrm(buf, s, n2+1);
     }
     result = PyUnicode_FromWideChar(buf, n2);
  exit: