Don't remove the transaction from the passed options object when doing setX in a…

… has-many. Closes #1789

lib/associations/has-many-double-linked.js

@@ -82,7 +82,8 @@ module.exports = (function() {
 
     if ((defaultAttributes || {}).transaction instanceof Transaction) {
       options.transaction = defaultAttributes.transaction;
-      delete defaultAttributes.transaction;
+
+      defaultAttributes = Utils._.omit(defaultAttributes, 'transaction'); // Don't try to insert the transaction as an attribute in the through table
     }
 
     unassociatedObjects = newAssociations.filter(function(obj) {

lib/associations/has-many-single-linked.js

@@ -44,7 +44,6 @@ module.exports = (function() {
 
     if ((defaultAttributes || {}).transaction instanceof Transaction) {
       options.transaction = defaultAttributes.transaction;
-      delete defaultAttributes.transaction;
     }
 
     if (obsoleteAssociations.length > 0) {