Index: oak-core/src/test/java/org/apache/jackrabbit/oak/security/authorization/AccessControlManagerImplTest.java
===================================================================
--- oak-core/src/test/java/org/apache/jackrabbit/oak/security/authorization/AccessControlManagerImplTest.java	(revision 1447782)
+++ oak-core/src/test/java/org/apache/jackrabbit/oak/security/authorization/AccessControlManagerImplTest.java	(working copy)
@@ -557,7 +557,6 @@
         // TODO
     }
 
-    @Ignore("OAK-644")
     @Test
     public void testSetPolicy() throws Exception {
         ACL acl = getApplicablePolicy(testPath);
@@ -576,7 +575,6 @@
         assertArrayEquals(acl.getAccessControlEntries(), acl2.getAccessControlEntries());
     }
 
-    @Ignore("OAK-644")
     @Test
     public void testSetPolicyWritesAcContent() throws Exception {
         ACL acl = getApplicablePolicy(testPath);
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/security/privilege/PrivilegeDefinitionStore.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/security/privilege/PrivilegeDefinitionStore.java	(revision 1447782)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/security/privilege/PrivilegeDefinitionStore.java	(working copy)
@@ -110,6 +110,9 @@
         }
         PrivilegeBits bits = PrivilegeBits.getInstance();
         for (String privilegeName : privilegeNames) {
+            if (privilegeName == null) {
+                break;
+            }
             Tree defTree = privilegesTree.getChild(privilegeName);
             if (defTree != null) {
                 bits.add(PrivilegeBits.getInstance(defTree));