[Dovecot] dovecot bug - kevent(EV_DELETE, 9)

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> dovecot works fine with AD! but i have this in logs (This not nice,
> but no more):
> Aug 14 02:21:03 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting
> Aug 14 02:21:03 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor 
> Aug 14 02:36:04 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting 
> Aug 14 02:36:04 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor 
> Aug 14 02:51:04 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting 
> Aug 14 02:51:04 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor 
> Aug 14 03:06:05 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting 
> Aug 14 03:06:05 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor 
> Aug 14 03:21:05 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting 
> Aug 14 03:21:05 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor 
> Aug 14 03:36:06 somecomp dovecot: auth(default): LDAP: Connection
> lost to LDAP server, reconnecting 
> Aug 14 03:36:06 somecomp dovecot: auth(default):
> kevent(EV_DELETE, 9) failed: Bad file descriptor

I understand. Windows 2003 close idle connections every 15 minutes (that policy set by default
in any windows 2003 server) and dovecot reconnects with this error.

Unfortunately dovecot haven't "keep-alive" parameter to keep
connection to LDAP alive (not idle). :(
And only that parameter can resolve my problem.