Replace PyObject_Unicode with PyObject_Str everywhere, and remove the
#define for PyObject_Unicode in object.h.
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 9342b19..bacc9ef 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -2444,7 +2444,7 @@
 
 	/* if the format is zero length, return str(self) */
 	if (PyUnicode_GetSize(format) == 0)
-                return PyObject_Unicode((PyObject *)self);
+                return PyObject_Str((PyObject *)self);
 
         return PyObject_CallMethod((PyObject *)self, "strftime", "O", format);
 }
@@ -3220,7 +3220,7 @@
 
 	/* if the format is zero length, return str(self) */
 	if (PyUnicode_GetSize(format) == 0)
-                return PyObject_Unicode((PyObject *)self);
+                return PyObject_Str((PyObject *)self);
 
         return PyObject_CallMethod((PyObject *)self, "strftime", "O", format);
 }