Fix selecting a field in non-interactive mode

The command:
boobank ing history blabla@ing -f table -s label,amount,date
was bugued, since b770163d9b.

Before to iter the history, boobank uses the get_object method, with fields set to []. The goal is to not use the selected_fields configured by the user.

But the commit b770163d9b added:
"or self.selected_fields"
Since "if []" return false, it cannot works.

weboob/tools/application/repl.py

@@ -351,12 +351,12 @@ class ReplApplication(Cmd, ConsoleApplication):
                     kwargs['backends'].append(backend)
         else:
             kwargs['backends'] = backends
-
-        fields = kwargs.pop('fields', self.selected_fields) or self.selected_fields
-        if '$direct' in fields:
-            fields = []
-        elif '$full' in fields:
-            fields = None
+        fields = kwargs.pop('fields', self.selected_fields)
+        if not fields and fields != []:
+            if '$direct' in fields:
+                fields = []
+            elif '$full' in fields:
+                fields = None
         return self.weboob.do(self._do_complete, self.options.count, fields, function, *args, **kwargs)
 
     # -- command tools ------------