Check for new record only when saving an actual current record

49cbc9b99ed8 added the calculation of a new variable but before the test that a
current record is actually being saved.

Closes #13946
(grafted from 383b2df462a149197e6e795d595aa3ae1d07f611)

--HG--
branch : 6.0

sao/src/screen.js

@@ -1568,7 +1568,6 @@
         },
         save_current: function() {
             var current_record = this.current_record;
-            let new_record = current_record.id < 0;
             if (!current_record) {
                 if (this.current_view &&
                     (this.current_view.view_type == 'tree') &&
@@ -1579,6 +1578,7 @@
                     return jQuery.when();
                 }
             }
+            let new_record = current_record.id < 0;
             if (this.current_view) {
                 this.current_view.set_value();
                 var fields = this.current_view.get_fields();