Bug 798629 - gnucash crashes attempting to import OFX file

It's not correct to g_free id if the g_hash_table_insert returns
FALSE; returning FALSE means the key/value pair was replaced. The key
will automatically be freed by glib thanks to the new_hash having a
GDestroyNotify g_free:

        GHashTable* new_hash = g_hash_table_new_full
            (g_str_hash, g_str_equal, g_free, NULL);

gnucash/import-export/import-backend.c

@@ -1219,8 +1219,7 @@ gboolean gnc_import_exists_online_id (Transaction *trans, GHashTable* acct_id_ha
             if (gnc_import_split_has_online_id (n->data))
             {
                 char *id = gnc_import_get_split_online_id (n->data);
-                if (!g_hash_table_insert (new_hash, (void*) id, GINT_TO_POINTER (1)))
-                    g_free (id);
+                g_hash_table_insert (new_hash, (void*) id, GINT_TO_POINTER (1));
             }
         }
     }