Issue #16980: Fix processing of escaped non-ascii bytes in the

unicode-escape-decode decoder.

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 3.3.1?
 Core and Builtins
 -----------------
 
+- Issue #16980: Fix processing of escaped non-ascii bytes in the
+  unicode-escape-decode decoder.
+
 - Issue #16975: Fix error handling bug in the escape-decode bytes decoder.
 
 - Issue #14850: Now a charmap decoder treats U+FFFE as "undefined mapping"

Objects/unicodeobject.c

@@ -5725,7 +5725,7 @@ PyUnicode_DecodeUnicodeEscape(const char *s,
             }
             else {
                 WRITECHAR('\\');
-                WRITECHAR(s[-1]);
+                WRITECHAR((unsigned char)s[-1]);
             }
             break;
         }