HostServiceBlacklist: small fixes

refs #907

library/Director/Db/Cache/PrefetchCache.php

@@ -108,6 +108,7 @@ class PrefetchCache
     {
         if ($this->hostServiceBlacklist === null) {
             $this->hostServiceBlacklist = new HostServiceBlacklist($this->db);
+            $this->hostServiceBlacklist->preloadMappings();
         }
 
         return $this->hostServiceBlacklist;

library/Director/Objects/IcingaService.php

@@ -413,7 +413,7 @@ class IcingaService extends IcingaObject
         if (! empty($blacklist)) {
             if (count($blacklist) === 1) {
                 $output .= sprintf(
-                    "    ignore host.name == %s\n",
+                    "    ignore where host.name == %s\n",
                     c::renderString($blacklist[0])
                 );
             } else {

library/Director/Resolver/HostServiceBlacklist.php

@@ -61,6 +61,10 @@ class HostServiceBlacklist
 
     public function fetchMappingsForService(IcingaService $service)
     {
+        if (! $service->hasBeenLoadedFromDb()) {
+            return [];
+        }
+
         $db = $this->db->getDbAdapter();
         $query = $db->select()->from(['hsb' => $this->table], [
             'host_name' => 'h.object_name',