Log error if we can't throw it

Author: holdenk

core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java

@@ -158,6 +158,9 @@ public void write(scala.collection.Iterator<Product2<K, V>> records) throws IOEx
           // error.
           if (success) {
             throw e;
+          } else {
+            logger.error("In addition to a failure during writing, we failed during " +
+                         "cleanup.", e);
           }
         }
       }