[TEST] fix BytesReference tests to never have a negative slice offset

test/framework/src/main/java/org/elasticsearch/common/bytes/AbstractBytesReferenceTestCase.java

@@ -432,7 +432,7 @@ public abstract class AbstractBytesReferenceTestCase extends ESTestCase {
     }
 
     public void testSliceArrayOffset() throws IOException {
-        int length = randomInt(PAGE_SIZE * randomIntBetween(2, 5));
+        int length = randomIntBetween(1, PAGE_SIZE * randomIntBetween(2, 5));
         BytesReference pbr = newBytesReference(length);
         int sliceOffset = randomIntBetween(0, pbr.length() - 1); // an offset to the end would be len 0
         int sliceLength = randomIntBetween(1, pbr.length() - sliceOffset);