check, per request by Jeff Davis.
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/port/unix_latch.c,v 1.2 2010/09/11 16:26:04 heikki Exp $
+ *       $PostgreSQL: pgsql/src/backend/port/unix_latch.c,v 1.3 2010/09/13 18:01:20 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
        if (selfpipe_readfd == -1)
                initSelfPipe();
 
+       /* sanity check */
        if (latch->owner_pid != 0)
                elog(ERROR, "latch already owned");
        latch->owner_pid = MyProcPid;