Merge mysql-5.1 to mysql-5.5.

storage/innobase/page/page0zip.c

 /*****************************************************************************
 
-Copyright (c) 2005, 2011, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2005, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -837,12 +837,13 @@ page_zip_compress_node_ptrs(
 		c_stream->next_in = (byte*) rec;
 		c_stream->avail_in = rec_offs_data_size(offsets)
 			- REC_NODE_PTR_SIZE;
-		ut_ad(c_stream->avail_in);
 
+		if (c_stream->avail_in) {
 			err = deflate(c_stream, Z_NO_FLUSH);
 			if (UNIV_UNLIKELY(err != Z_OK)) {
 				break;
 			}
+		}
 
 		ut_ad(!c_stream->avail_in);