Disable save button on `QfqForm#handleConflict()`.

javascript/src/QfqForm.js

@@ -792,6 +792,11 @@ var QfqNS = QfqNS || {};
      *
      */
     n.QfqForm.prototype.handleConflict = function (form, data) {
+        this.setButtonEnabled(this.getSaveButton(), false);
+        this.getSaveButton().removeClass(this.getSaveButtonAttentionClass());
+        this.setButtonEnabled(this.getDeleteButton(), false);
+        this.formImmutableDueToConcurrentAccess = true;
+        this.lockAcquired = false;
         var alert = new n.Alert(data.message, "error");
         alert.show();
     };