Use of 8192 as BLCKSZ in xlog.c

In two of the sections covered by #ifdef WAL_DEBUG there are 
declarations like:

char        buf[8192];

It seems to me that these should be:

char        buf[BLCKSZ];

- or have I misunderstood what is going on here?

I realize that it's probably not terribly significant, as most people 
will do development with BLCKSZ=8192 anyway - I'm just trying to 
understand the code ... :-).

regards

Mark