CRM-13085 - Fix premature transaction commit stemming from TRUNCATE TABLE civicrm_acl_contact_cache

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* CRM-13085: Transaction rollback doesn't work with contact creation (due to ACL TRUNCATE)
  http://issues.civicrm.org/jira/browse/CRM-13085

CRM/ACL/BAO/Cache.php

@@ -140,7 +140,15 @@ WHERE  modified_date IS NULL
 ";
     CRM_Core_DAO::singleValueQuery($query);
 
-    CRM_Core_DAO::singleValueQuery("TRUNCATE TABLE civicrm_acl_contact_cache");
+    // CRM_Core_DAO::singleValueQuery("TRUNCATE TABLE civicrm_acl_contact_cache"); // No, force-commits transaction
+    // CRM_Core_DAO::singleValueQuery("DELETE FROM civicrm_acl_contact_cache"); // Transaction-safe
+    if (CRM_Core_Transaction::isActive()) {
+      CRM_Core_Transaction::addCallback(CRM_Core_Transaction::PHASE_POST_COMMIT, function(){
+        CRM_Core_DAO::singleValueQuery("TRUNCATE TABLE civicrm_acl_contact_cache");
+      });
+    } else {
+      CRM_Core_DAO::singleValueQuery("TRUNCATE TABLE civicrm_acl_contact_cache");
+    }
   }
 }