This reverts r63675 based on the discussion in this thread:

 http://mail.python.org/pipermail/python-dev/2008-June/079988.html

Python 2.6 should stick with PyString_* in its codebase.  The PyBytes_* names
in the spirit of 3.0 are available via a #define only.  See the email thread.
diff --git a/Modules/binascii.c b/Modules/binascii.c
index f9df625..c1fc675 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -141,7 +141,7 @@
 #define BASE64_PAD '='
 
 /* Max binary chunk size; limited only by available memory */
-#define BASE64_MAXBIN (INT_MAX/2 - sizeof(PyBytesObject) - 3)
+#define BASE64_MAXBIN (INT_MAX/2 - sizeof(PyStringObject) - 3)
 
 static unsigned char table_b2a_base64[] =
 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
@@ -203,9 +203,9 @@
 	ascii_len--;
 
 	/* Allocate the buffer */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, bin_len)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )
 		return NULL;
-	bin_data = (unsigned char *)PyBytes_AsString(rv);
+	bin_data = (unsigned char *)PyString_AsString(rv);
 
 	for( ; bin_len > 0 ; ascii_len--, ascii_data++ ) {
 		/* XXX is it really best to add NULs if there's no more data */
@@ -280,9 +280,9 @@
 	}
 
 	/* We're lazy and allocate to much (fixed up later) */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, bin_len*2+2)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2+2)) == NULL )
 		return NULL;
-	ascii_data = (unsigned char *)PyBytes_AsString(rv);
+	ascii_data = (unsigned char *)PyString_AsString(rv);
 
 	/* Store the length */
 	*ascii_data++ = ' ' + (bin_len & 077);
@@ -304,8 +304,8 @@
 	}
 	*ascii_data++ = '\n';	/* Append a courtesy newline */
 
-	_PyBytes_Resize(&rv, (ascii_data -
-			       (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(&rv, (ascii_data -
+			       (unsigned char *)PyString_AsString(rv)));
 	return rv;
 }
 
@@ -354,9 +354,9 @@
 	bin_len = ((ascii_len+3)/4)*3; /* Upper bound, corrected later */
 
 	/* Allocate the buffer */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, bin_len)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )
 		return NULL;
-	bin_data = (unsigned char *)PyBytes_AsString(rv);
+	bin_data = (unsigned char *)PyString_AsString(rv);
 	bin_len = 0;
 
 	for( ; ascii_len > 0; ascii_len--, ascii_data++) {
@@ -415,13 +415,13 @@
 
 	/* And set string size correctly. If the result string is empty
 	** (because the input was all invalid) return the shared empty
-	** string instead; _PyBytes_Resize() won't do this for us.
+	** string instead; _PyString_Resize() won't do this for us.
 	*/
 	if (bin_len > 0)
-		_PyBytes_Resize(&rv, bin_len);
+		_PyString_Resize(&rv, bin_len);
 	else {
 		Py_DECREF(rv);
-		rv = PyBytes_FromString("");
+		rv = PyString_FromString("");
 	}
 	return rv;
 }
@@ -448,9 +448,9 @@
 	/* We're lazy and allocate too much (fixed up later).
 	   "+3" leaves room for up to two pad characters and a trailing
 	   newline.  Note that 'b' gets encoded as 'Yg==\n' (1 in, 5 out). */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, bin_len*2 + 3)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2 + 3)) == NULL )
 		return NULL;
-	ascii_data = (unsigned char *)PyBytes_AsString(rv);
+	ascii_data = (unsigned char *)PyString_AsString(rv);
 
 	for( ; bin_len > 0 ; bin_len--, bin_data++ ) {
 		/* Shift the data into our buffer */
@@ -474,8 +474,8 @@
 	}
 	*ascii_data++ = '\n';	/* Append a courtesy newline */
 
-	_PyBytes_Resize(&rv, (ascii_data -
-			       (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(&rv, (ascii_data -
+			       (unsigned char *)PyString_AsString(rv)));
 	return rv;
 }
 
@@ -498,9 +498,9 @@
 	/* Allocate a string that is too big (fixed later) 
 	   Add two to the initial length to prevent interning which
 	   would preclude subsequent resizing.  */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, len+2)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, len+2)) == NULL )
 		return NULL;
-	bin_data = (unsigned char *)PyBytes_AsString(rv);
+	bin_data = (unsigned char *)PyString_AsString(rv);
 
 	for( ; len > 0 ; len--, ascii_data++ ) {
 		/* Get the byte and look it up */
@@ -534,8 +534,8 @@
 		Py_DECREF(rv);
 		return NULL;
 	}
-	_PyBytes_Resize(
-		&rv, (bin_data - (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(
+		&rv, (bin_data - (unsigned char *)PyString_AsString(rv)));
 	if (rv) {
 		PyObject *rrv = Py_BuildValue("Oi", rv, done);
 		Py_DECREF(rv);
@@ -559,9 +559,9 @@
 		return NULL;
 
 	/* Worst case: output is twice as big as input (fixed later) */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, len*2+2)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, len*2+2)) == NULL )
 		return NULL;
-	out_data = (unsigned char *)PyBytes_AsString(rv);
+	out_data = (unsigned char *)PyString_AsString(rv);
 
 	for( in=0; in<len; in++) {
 		ch = in_data[in];
@@ -587,8 +587,8 @@
 			}
 		}
 	}
-	_PyBytes_Resize(&rv, (out_data -
-			       (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(&rv, (out_data -
+			       (unsigned char *)PyString_AsString(rv)));
 	return rv;
 }
 
@@ -608,9 +608,9 @@
 		return NULL;
 
 	/* Allocate a buffer that is at least large enough */
-	if ( (rv=PyBytes_FromStringAndSize(NULL, len*2+2)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, len*2+2)) == NULL )
 		return NULL;
-	ascii_data = (unsigned char *)PyBytes_AsString(rv);
+	ascii_data = (unsigned char *)PyString_AsString(rv);
 
 	for( ; len > 0 ; len--, bin_data++ ) {
 		/* Shift into our buffer, and output any 6bits ready */
@@ -627,8 +627,8 @@
 		leftchar <<= (6-leftbits);
 		*ascii_data++ = table_b2a_hqx[leftchar & 0x3f];
 	}
-	_PyBytes_Resize(&rv, (ascii_data -
-			       (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(&rv, (ascii_data -
+			       (unsigned char *)PyString_AsString(rv)));
 	return rv;
 }
 
@@ -647,14 +647,14 @@
 
 	/* Empty string is a special case */
 	if ( in_len == 0 )
-		return PyBytes_FromString("");
+		return PyString_FromString("");
 
 	/* Allocate a buffer of reasonable size. Resized when needed */
 	out_len = in_len*2;
-	if ( (rv=PyBytes_FromStringAndSize(NULL, out_len)) == NULL )
+	if ( (rv=PyString_FromStringAndSize(NULL, out_len)) == NULL )
 		return NULL;
 	out_len_left = out_len;
-	out_data = (unsigned char *)PyBytes_AsString(rv);
+	out_data = (unsigned char *)PyString_AsString(rv);
 
 	/*
 	** We need two macros here to get/put bytes and handle
@@ -673,9 +673,9 @@
 #define OUTBYTE(b) \
 	do { \
 		 if ( --out_len_left < 0 ) { \
-			  _PyBytes_Resize(&rv, 2*out_len); \
+			  _PyString_Resize(&rv, 2*out_len); \
 			  if ( rv == NULL ) return NULL; \
-			  out_data = (unsigned char *)PyBytes_AsString(rv) \
+			  out_data = (unsigned char *)PyString_AsString(rv) \
 								 + out_len; \
 			  out_len_left = out_len-1; \
 			  out_len = out_len * 2; \
@@ -723,8 +723,8 @@
 			OUTBYTE(in_byte);
 		}
 	}
-	_PyBytes_Resize(&rv, (out_data -
-			       (unsigned char *)PyBytes_AsString(rv)));
+	_PyString_Resize(&rv, (out_data -
+			       (unsigned char *)PyString_AsString(rv)));
 	return rv;
 }
 
@@ -923,10 +923,10 @@
 	if (!PyArg_ParseTuple(args, "s#:b2a_hex", &argbuf, &arglen))
 		return NULL;
 
-	retval = PyBytes_FromStringAndSize(NULL, arglen*2);
+	retval = PyString_FromStringAndSize(NULL, arglen*2);
 	if (!retval)
 		return NULL;
-	retbuf = PyBytes_AsString(retval);
+	retbuf = PyString_AsString(retval);
 	if (!retbuf)
 		goto finally;
 
@@ -989,10 +989,10 @@
 		return NULL;
 	}
 
-	retval = PyBytes_FromStringAndSize(NULL, (arglen/2));
+	retval = PyString_FromStringAndSize(NULL, (arglen/2));
 	if (!retval)
 		return NULL;
-	retbuf = PyBytes_AsString(retval);
+	retbuf = PyString_AsString(retval);
 	if (!retbuf)
 		goto finally;
 
@@ -1106,7 +1106,7 @@
 			out++;
 		}
 	}
-	if ((rv = PyBytes_FromStringAndSize((char *)odata, out)) == NULL) {
+	if ((rv = PyString_FromStringAndSize((char *)odata, out)) == NULL) {
 		PyMem_Free(odata);
 		return NULL;
 	}
@@ -1306,7 +1306,7 @@
 			}
 		}
 	}
-	if ((rv = PyBytes_FromStringAndSize((char *)odata, out)) == NULL) {
+	if ((rv = PyString_FromStringAndSize((char *)odata, out)) == NULL) {
 		PyMem_Free(odata);
 		return NULL;
 	}
@@ -1354,7 +1354,7 @@
 		return;
 
 	d = PyModule_GetDict(m);
-	x = PyBytes_FromString(doc_binascii);
+	x = PyString_FromString(doc_binascii);
 	PyDict_SetItemString(d, "__doc__", x);
 	Py_XDECREF(x);