Fix test edge case for random bytes reference iter.

Getting an offset to the last byte means we can only stream one byte and
then we are done, we can't get another offset after it.

core/src/test/java/org/elasticsearch/common/bytes/AbstractBytesReferenceTestCase.java

@@ -271,6 +271,9 @@ public abstract class AbstractBytesReferenceTestCase extends ESTestCase {
                 final int offset = randomIntBetween(0, length-1);
                 assertEquals(offset, input.skip(offset));
                 assertEquals(pbr.get(offset), input.readByte());
+                if (offset == length - 1) {
+                    continue; // no more bytes to retrieve!
+                }
                 final int nextOffset = randomIntBetween(offset, length-2);
                 assertEquals(nextOffset - offset, input.skip(nextOffset - offset));
                 assertEquals(pbr.get(nextOffset+1), input.readByte()); // +1 for the one byte we read above