Report handbrake failure to client

Added check on return status of handbrake process, and reports failure
to cluster client.
Fixed a bug whereby handbrake processes were not reaped after the rip
completes

handbrake-cluster-worker.pl

@@ -125,6 +125,16 @@ sub do_rip {
     while ($line = <$child_out>) {
         $log->debug($line);
     }
+    close($child_out);
+
+    # If the rip process failed, report an error status here
+    waitpid($child_pid, 0);
+    my $child_exit_status = $? >> 8;
+
+    if (!$child_exit_status) {
+        $log->warning("Ripping process returned error status: $child_exit_status");
+        return undef;
+    }
 
     $log->notice("Finished rip to $rip_filename");
     return $rip_filename;