[pkg-ntp-maintainers] Capabilities problem in new ntp

[Peter Eisentraut]

ntp 4.2.4p0, which is currently in svn, doesn't appear to work out of the box.  
I get this error message in the log:

cap_set_proc() failed to drop root privileges: Operation not permitted

The relevant code is

   char *captext = interface_interval ?
           "cap_sys_time,cap_net_bind_service=ipe" :
           "cap_sys_time=ipe";
   if( ! ( caps = cap_from_text( captext ) ) ) {
           msyslog( LOG_ERR, "cap_from_text() failed: %m" );
           exit(-1);
   }
   if( cap_set_proc( caps ) == -1 ) {
           msyslog( LOG_ERR, "cap_set_proc() failed to drop root 
privileges: %m" );
           exit(-1);
   }

If I disable the interface_interval thing by passing the option -U 0 (e.g., 
via /etc/default/ntp), then we get the "cap_sys_time=ipe" string which 
corresponds to the old 4.2.2 behavior, and that indeed works.

Does anyone know why the cap_net_bind_service capability cannot be set?