fix the issue found on IRC this morning. The logging call was mistructured

so threw and exception when attempting to log that we missed an asset and
were waiting for it.

OpenSim/Framework/Communications/Cache/AssetCache.cs

@@ -198,7 +198,8 @@ namespace OpenSim.Framework.Communications.Cache
             } while (--maxPolls > 0);
 
             m_log.Warn(
-                String.Format("[ASSETCACHE]: Asset {0} was not received before the retrieval timeout was reached"));
+                       String.Format("[ASSETCACHE]: Asset {0} was not received before the retrieval timeout was reached", assetID.ToString())
+                );
 
             return null;
         }