Description of problem: This essentially another occurence of bug 570393, but in the system.getSubscribedBaseChannel API call.  If the system in question does not have a base channel, this call returns nothing and thus an error is seen from the script.

#!/usr/bin/perl
use Frontier::Client;

my $HOST = 'jrummy5-sat.example.com';
my $user = 'admin';
my $pass = 'xxxxxx';

my $client = new Frontier::Client(url => "http://$HOST/rpc/api");
my $session = $client->call('auth.login',$user, $pass);

my $systems = $client->call('system.getId', $session, "jrummy5-64");
foreach my $system (@$systems) {
       print $system->{'name'}.":".$system->{'id'}."\n";
       $chaninfo = $client->call('system.getSubscribedBaseChannel', $session, $system->{'id'});        
}
$client->call('auth.logout', $session); 

# ./api.pl 
jrummy5-64:1000010177

no element found at line 1, column 0, byte -1 at /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/XML/Parser.pm line 187



Version-Release number of selected component (if applicable): sat 5.4

How reproducible: Always

Steps to Reproduce:
1. Register host to satellite
2. Remove base channel from system
3. Run above script, using that system's name
  
Actual results: no element found at line 1, column 0, byte -1 at /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/XML/Parser.pm line 187

Expected results: No error

Additional info: In bug 570393, I understand it was deemed that this problem should be fixed on the server, as the call should never return nothing.  However shouldn't we also fix the Frontier::Client so that this doesn't continue to happen for other calls that make the same mistake?