Index: oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessor.java
===================================================================
--- oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessor.java	(revision 1851611)
+++ oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessor.java	(working copy)
@@ -19,6 +19,8 @@
 
 package org.apache.jackrabbit.oak.segment.standby.client;
 
+import static org.apache.jackrabbit.oak.commons.IOUtils.closeQuietly;
+
 import java.io.IOException;
 import java.io.InputStream;
 
@@ -59,7 +61,59 @@
     }
 
     private boolean shouldFetchBinary(SegmentBlob blob) {
-        return blob.isExternal() && blob.getReference() == null && blob.getBlobId() != null;
+
+        // Shortcut: If the Blob ID is null, this is an inline binary and we
+        // don't have to fetch it.
+
+        String blobId = blob.getBlobId();
+
+        if (blobId == null) {
+            return false;
+        }
+
+        // Shortcut: If the Blob Store is able to retrieve a non-null reference
+        // to the Blob, we can be sure that the Blob is already stored locally.
+        // We don't have to download it.
+
+        String reference;
+
+        try {
+            reference = blob.getReference();
+        } catch (Exception e) {
+            reference = null;
+        }
+
+        if (reference != null) {
+            return false;
+        }
+
+        // Worst case: A null reference to the Blob might just mean that the
+        // Blob Store doesn't support references. The Blob might still be stored
+        // locally. We have to retrieve an InputStream for the Blob, and
+        // perform a tentative read in order to overcome a possible lazy
+        // implementation of the returned InputStream.
+
+        InputStream data;
+
+        try {
+            data = blobStore.getInputStream(blobId);
+        } catch (Exception e) {
+            return true;
+        }
+
+        if (data == null) {
+            return true;
+        }
+
+        try {
+            data.read();
+        } catch (Exception e) {
+            return true;
+        } finally {
+            closeQuietly(data);
+        }
+
+        return false;
     }
 
     private void fetchAndStoreBlob(String blobId) throws InterruptedException {
Index: oak-segment-tar/src/test/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessorTest.java
===================================================================
--- oak-segment-tar/src/test/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessorTest.java	(revision 1851611)
+++ oak-segment-tar/src/test/java/org/apache/jackrabbit/oak/segment/standby/client/RemoteBlobProcessorTest.java	(working copy)
@@ -33,7 +33,6 @@
 import org.apache.jackrabbit.oak.spi.commit.EmptyHook;
 import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.RuleChain;
@@ -85,7 +84,6 @@
      * downloaded.
      */
     @Test
-    @Ignore("OAK-6749")
     public void inMemoryBinaryShouldNotBeDownloaded() throws Exception {
         SegmentNodeStore store = SegmentNodeStoreBuilders.builder(fileStore.fileStore()).build();