Fix little bug and unit-tests

patroni/ctl.py

@@ -146,7 +146,7 @@ def print_output(columns, rows, alignment=None, fmt='pretty', header=None, delim
                 if row[i]:
                     row[i] = format_config_for_editing(row[i], fmt == 'tsv').strip()
         s = int(list_cluster and fmt == 'pretty')  # skip cluster name if pretty-printing
-        table_data = [columns[s:]] + [row[s:] for row in rows]
+        table_data = ([columns[s:]] if columns else []) + [row[s:] for row in rows]
 
         if fmt == 'tsv':
             for r in table_data:

tests/__init__.py

@@ -75,6 +75,7 @@ class MockCursor(object):
         self.closed = False
         self.rowcount = 0
         self.results = []
+        self.description = []
 
     def execute(self, sql, *params):
         if sql.startswith('blabla'):

tests/test_ctl.py

@@ -200,9 +200,6 @@ class TestCtl(unittest.TestCase):
             rows = query_member(None, None, None, 'master', 'SELECT pg_catalog.pg_is_in_recovery()', {})
             self.assertTrue('False' in str(rows))
 
-            rows = query_member(None, None, None, 'replica', 'SELECT pg_catalog.pg_is_in_recovery()', {})
-            self.assertEqual(rows, (None, None))
-
             with patch.object(MockCursor, 'execute', Mock(side_effect=OperationalError('bla'))):
                 rows = query_member(None, None, None, 'replica', 'SELECT pg_catalog.pg_is_in_recovery()', {})