Clear the value of input select once data has been read

The display does not clear the input if the current record is changed so we
must ensure that the input is always empty once file has been selected.

Closes #14482
(grafted from 759ffbf53e83eb67855b929aaf0274826e1b1fb5)

--HG--
branch : 8.0

sao/src/view/form.js

@@ -4521,11 +4521,12 @@ function eval_pyson(value){
                 field = this.field,
                 filename_field = this.filename_field;
 
-            Sao.common.get_input_data(this.input_select, function(data, filename) {
+            Sao.common.get_input_data(this.input_select, (data, filename) => {
                 field.set_client(record, data);
                 if (filename_field) {
                     filename_field.set_client(record, filename);
                 }
+                this.input_select.val(undefined);
             }, !field.get_size);
         },
         select_drop: function(evt) {