Update DBTCPConnector.java

We should catch the `MongoException` first. Otherwish, any `RuntimeException` (com.mongodb.MongoException$DuplicateKey for example) will cause connection closed.

Author: prisoner

src/main/com/mongodb/DBTCPConnector.java

@@ -217,6 +217,9 @@ <T> T doOperation(final DB db, final DBPort port, final DBPort.Operation<T> oper
             port.checkAuth( db.getMongo() );
             return operation.execute();
         }
+        catch ( MongoException re ){
+            throw re;
+        }
         catch ( IOException ioe ){
             _myPort.error(port, ioe);
             throw new MongoException.Network("Operation on server " + port.getAddress() + " failed" , ioe );