Postgresql startup: runuser: cannot set groups: operation not permitted

Question

I'm having trouble starting a postgres database. I'm running 9.2 on Centos 5.4 (for compatibility reasons). Here is what I have done so far:

• Ran postgres initdb for the directory /opt/database
• Updated postgresql.conf to increase sessions, use more of the available ram, and change logging.
• Started postgres as a test (it worked)
• Added a recovery.conf and changed pg_hba.conf to allow replication (this is a slave)
• Ran a pg_basebackup (as user postgres) to get a copy of data from the master

After the completion of the basebackup, I tried to start postgres and it fails with no error output. The only information I have is from the pgstartup.log which says:

runuser: cannot set groups: Operation not permitted

The runuser command has 2755 permissions (setgid sticky bit set). Because of something I found in another forum, I ran /usr/pgsql-9.2/bin/postgres -d 3 -D /opt/database -c config_file=/opt/database/postgresql.conf as user postgres. I received the following output (which has been trimmed to remove useless bits like my ls colors, and my ssh session information).

DEBUG:  postgres: PostmasterMain: initial environment dump:
DEBUG:  -----------------------------------------
DEBUG:      USER=postgres
DEBUG:      LD_LIBRARY_PATH=/usr/pgsql-9.2/lib
DEBUG:      PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
DEBUG:      _=/usr/pgsql-9.2/bin/postgres
DEBUG:      PWD=/opt/database
DEBUG:      INPUTRC=/etc/inputrc
DEBUG:      EDITOR=vim
DEBUG:      SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass
DEBUG:      HOME=/var/lib/pgsql
DEBUG:      SHLVL=2
DEBUG:      LOGNAME=postgres
DEBUG:      CVS_RSH=ssh
DEBUG:      LESSOPEN=|/usr/bin/lesspipe.sh %s
DEBUG:      G_BROKEN_FILENAMES=1
DEBUG:      HISTTIMEFORMAT=%F %T:
DEBUG:      PGLOCALEDIR=/usr/pgsql-9.2/share/locale
DEBUG:      PGSYSCONFDIR=/etc/sysconfig/pgsql
DEBUG:      LC_COLLATE=en_US.UTF-8
DEBUG:      LC_CTYPE=en_US.UTF-8
DEBUG:      LC_MESSAGES=en_US.utf8
DEBUG:  -----------------------------------------
DEBUG:  invoking IpcMemoryCreate(size=2220941312)
DEBUG:  SlruScanDirectory invoking callback on pg_notify/0000
DEBUG:  removing file "pg_notify/0000"
DEBUG:  max_safe_fds = 984, usable_fds = 1000, already_open = 6
bash-3.2$ DEBUG:  logger shutting down
DEBUG:  shmem_exit(0): 0 callbacks to make
DEBUG:  proc_exit(0): 0 callbacks to make
DEBUG:  exit(0)
DEBUG:  shmem_exit(-1): 0 callbacks to make
DEBUG:  proc_exit(-1): 0 callbacks to make

Any idea why postgres isn't starting?