Issue #4971: Fix titlecase for characters that are their own

titlecase, but not their own uppercase.

Lib/test/test_unicodedata.py

@@ -20,7 +20,7 @@ encoding = 'utf-8'
 class UnicodeMethodsTest(unittest.TestCase):
 
     # update this, if the database changes
-    expectedchecksum = 'b7db9b5f1d804976fa921d2009cbef6f025620c1'
+    expectedchecksum = '6ec65b65835614ec00634c674bba0e50cd32c189'
 
     def test_method_checksum(self):
         h = hashlib.sha1()
@@ -270,6 +270,11 @@ class UnicodeMiscTest(UnicodeDatabaseTest):
             [0]
         )
 
+    def test_buf_4971(self):
+        # LETTER DZ WITH CARON: DZ, Dz, dz
+        self.assertEqual(u"\u01c4".title(), u"\u01c5")
+        self.assertEqual(u"\u01c5".title(), u"\u01c5")
+        self.assertEqual(u"\u01c6".title(), u"\u01c5")
 
 def test_main():
     test.test_support.run_unittest(

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 2.7 alpha 1
 Core and Builtins
 -----------------
 
+- Issue #4971: Fix titlecase for characters that are their own
+  titlecase, but not their own uppercase.
+
 - Issue #5835: Deprecate PyOS_ascii_formatd and replace it with
   _PyOS_double_to_string or PyOS_double_to_string.
 

Objects/unicodectype.c

@@ -76,12 +76,7 @@ int _PyUnicode_IsLinebreak(register const Py_UNICODE ch)
 Py_UNICODE _PyUnicode_ToTitlecase(register Py_UNICODE ch)
 {
     const _PyUnicode_TypeRecord *ctype = gettyperecord(ch);
-    int delta;
-
-    if (ctype->title)
-        delta = ctype->title;
-    else
-	delta = ctype->upper;
+    int delta = ctype->title;
 
     if (ctype->flags & NODELTA_MASK)
 	return delta;