Merge pull request #1050 from druid-io/fix-rt

Fix a small bug where an NPE can occur if a closeable is not present

server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java

@@ -288,8 +288,10 @@ public class RealtimePlumber implements Plumber
                                             }
                                             finally {
                                               try {
+                                                if (closeable != null) {
                                                   closeable.close();
                                                 }
+                                              }
                                               catch (IOException e) {
                                                 throw Throwables.propagate(e);
                                               }