Why does WAL_DEBUG macro need to be defined by default?

Hi,

I found that by default WAL_DEBUG macro has been defined in
9.2dev and 9.1. I'm very surprised at this. Why does WAL_DEBUG
need to be defined by default? The performance overhead
introduced by WAL_DEBUG is really vanishingly low?

WAL_DEBUG was defined in the following commit:
53dbc27c62d8e1b6c5253feba04a5094cb8fe046

----------------------   Support unlogged tables.
   The contents of an unlogged table are WAL-logged; thus, they are not   available on standby servers and are
truncatedwhenever the database   system enters recovery.  Indexes on unlogged tables are also unlogged.   Unlogged GiST
indexesare not currently supported.
 
----------------------

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center