Serhiy Storchaka, would you review again?

Merging unicodeobject.c.v5.patch into default branch was almost straightforward.
But there was one place I should rewrite.  Here is the part of diff -u v5.patch v6.patch

-- is old docstring w/o AC
+- is current docstring w/o AC
-+ is AC in v5 patch
++ is AC in v6 patch

 -PyDoc_STRVAR(translate__doc__,
 -             "S.translate(table) -> str\n\
 -\n\
--Return a copy of the string S, where all characters have been mapped\n\
--through the given translation table, which must be a mapping of\n\
--Unicode ordinals to Unicode ordinals, strings, or None.\n\
--Unmapped characters are left untouched. Characters mapped to None\n\
--are deleted.");
+-Return a copy of the string S in which each character has been mapped\n\
+-through the given translation table. The table must implement\n\
+-lookup/indexing via __getitem__, for instance a dictionary or list,\n\
+-mapping Unicode ordinals to Unicode ordinals, strings, or None. If\n\
+-this operation raises LookupError, the character is left untouched.\n\
+-Characters mapped to None are deleted.");
 -
 -static PyObject*
 +/*[clinic input]
@@ -1194,14 +1271,14 @@
 +
 +Replace each character in the string using the given translation table.
 +
-+Characters not in the translation table are left untouched.
-+
-+Characters mapped to None are deleted.
++The table must implement lookup/indexing via __getitem__, for instance a
++dictionary or list.  If this operation raises LookupError, the character is
++left untouched.  Characters mapped to None are deleted.
 +[clinic start generated code]*/