Fix without result

tests/test_types.py

@@ -44,6 +44,10 @@ class TestSortedCorrectedCommandsSequence(object):
         assert set(seq) == {CorrectedCommand('ls', priority=100),
                             CorrectedCommand('ls', side_effect, 300)}
 
+    def test_with_blank(self, settings):
+        seq = SortedCorrectedCommandsSequence(iter([]), settings)
+        assert list(seq) == []
+
 
 class TestCorrectedCommand(object):
 

thefuck/types.py

@@ -81,6 +81,7 @@ class SortedCorrectedCommandsSequence(object):
 
     def _realise(self):
         """Realises generator, removes duplicates and sorts commands."""
+        if self._cached:
             commands = self._remove_duplicates(self._commands)
             self._cached = [self._cached[0]] + sorted(
                 commands, key=lambda corrected_command: corrected_command.priority)