initdb using option "username" startup log - Mailing list pgsql-bugs

I initdb like below
"initdb --pgdata=/pg_data --encoding='utf8' --locale='C' --lc-collate='C'
--lc-ctype='C' --username=sys --pwprompt"

When startup database server.
Server wirte log like this
-----------------------------
LOG:  database system was shut down at 2012-10-31 12:00:14 KST
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started
FATAL:  role "postgres" does not exist
-----------------------------

*What is it ? : FATAL:  role "postgres" does not exist*

P.S process list
[postgres@pg111 pg_log]$ ps auxww | grep ^postgres
postgres 13920  0.0  0.0 108300  1952 pts/1    S    10:54   0:00 -bash
postgres 14588  0.0  0.1 153732  7108 ?        S    12:00   0:00
/postgresql/9.2.1/bin/postgres -D /pg_data
postgres 14590  0.0  0.0 153732   940 ?        Ss   12:00   0:00 postgres:
checkpointer process
postgres 14591  0.0  0.0 153732  1004 ?        Ss   12:00   0:00 postgres:
writer process
postgres 14592  0.0  0.0 153732   900 ?        Ss   12:00   0:00 postgres:
wal writer process
postgres 14593  0.0  0.0 154432  1908 ?        Ss   12:00   0:00 postgres:
autovacuum launcher process
postgres 14594  0.0  0.0 113420   788 ?        Ss   12:00   0:00 postgres:
stats collector process
postgres 14612  0.0  0.0 110224  1152 pts/1    R+   12:01   0:00 ps auxww
postgres 14613  0.0  0.0 103236   864 pts/1    S+   12:01   0:00 grep
^postgres


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