prefork mupdate slaves

[Andrew Morgan]

With the following service entry on a traditional murder frontend 
(v2.3.10):

   mupdate       cmd="/usr/local/cyrus/bin/mupdate" listen="3905" prefork=1

I notice that 2 mupdate processes are spawned at startup:

Nov 21 14:43:43 cyrus-fe3 mupdate[6935]: successful mupdate connection to cyrus-mm.onid.oregonstate.edu
Nov 21 14:43:43 cyrus-fe3 mupdate[6935]: unready for connections
Nov 21 14:43:43 cyrus-fe3 mupdate[6935]: synchronizing mailbox list with master mupdate server
Nov 21 14:43:43 cyrus-fe3 mupdate[6931]: successful mupdate connection to cyrus-mm.onid.oregonstate.edu
Nov 21 14:43:43 cyrus-fe3 mupdate[6931]: unready for connections
Nov 21 14:43:43 cyrus-fe3 mupdate[6931]: synchronizing mailbox list with master mupdate server
Nov 21 14:43:48 cyrus-fe3 mupdate[6935]: mailbox list synchronization complete
Nov 21 14:43:52 cyrus-fe3 mupdate[6931]: mailbox list synchronization complete

And those 2 mupdate processes remain running.

If I set prefork=0, then no mupdate processes are ever spawned, as far as 
I can tell.

On my old v2.2.13 murder frontends, prefork=1 only causes 1 mupdate 
process to be spawned.

Is this a bug?  Should I be concerned that 2 mupdate slaves are running?

Thanks,
 	Andy