diff -r e5a78f7c2dcb Lib/test/test_codecs.py
--- a/Lib/test/test_codecs.py	Fri Feb 07 10:06:39 2014 +0200
+++ b/Lib/test/test_codecs.py	Fri Feb 07 19:46:39 2014 +0200
@@ -852,13 +852,40 @@
 
     def test_partial(self):
         self.check_partial(
-            "a+-b",
+            'a+-b\x00c\x80d\u0100e\U00010000f',
             [
-                "a",
-                "a",
-                "a+",
-                "a+-",
-                "a+-b",
+                'a',
+                'a',
+                'a+',
+                'a+-',
+                'a+-b',
+                'a+-b',
+                'a+-b',
+                'a+-b',
+                'a+-b',
+                'a+-b\x00',
+                'a+-b\x00c',
+                'a+-b\x00c',
+                'a+-b\x00c',
+                'a+-b\x00c',
+                'a+-b\x00c',
+                'a+-b\x00c\x80',
+                'a+-b\x00c\x80d',
+                'a+-b\x00c\x80d',
+                'a+-b\x00c\x80d',
+                'a+-b\x00c\x80d',
+                'a+-b\x00c\x80d',
+                'a+-b\x00c\x80d\u0100',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e',
+                'a+-b\x00c\x80d\u0100e\U00010000',
+                'a+-b\x00c\x80d\u0100e\U00010000f',
             ]
         )
 
diff -r e5a78f7c2dcb Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Fri Feb 07 10:06:39 2014 +0200
+++ b/Objects/unicodeobject.c	Fri Feb 07 19:46:39 2014 +0200
@@ -4474,8 +4474,16 @@
     /* return state */
     if (consumed) {
         if (inShift) {
+            *consumed = startinpos;
+            if (outpos != shiftOutStart &&
+                PyUnicode_MAX_CHAR_VALUE(unicode) > 127) {
+                PyObject *result = PyUnicode_FromKindAndData(
+                        PyUnicode_KIND(unicode), PyUnicode_DATA(unicode),
+                        shiftOutStart);
+                Py_DECREF(unicode);
+                unicode = result;
+            }
             outpos = shiftOutStart; /* back off output */
-            *consumed = startinpos;
         }
         else {
             *consumed = s-starts;