Compatibility with prettytable 2.2.0+ (#2436)

`patronictl list` and `patronictl topology` didn't worked correctly starting from prettytable 2.2.0 (https://github.com/jazzband/prettytable/pull/104).
Example of wrong output:
```
+----------+-----------+---------+---------+----+-----------+
| Member   | Host      | Role    | State   | TL | Lag in MB |
+ Cluster: demo-cluster-1 (7155048679605235377) +-----------+
| node-2   | 10.2.0.21 | Leader  | running |  1 |           |
| + node-1 | 10.2.0.6  | Replica | running |  1 |         0 |
| + node-3 | 10.2.0.25 | Replica | running |  1 |         0 |
+----------+-----------+---------+---------+----+-----------+
```

patroni/ctl.py

@@ -60,6 +60,18 @@ class PatronictlPrettyTable(PrettyTable):
         self.__hline_num = 0
         self.__hline = None
 
+    def __build_header(self, line):
+        header = self.__table_header[:len(line) - 2]
+        return "".join([line[0], header, line[1 + len(header):]])
+
+    def _stringify_hrule(self, *args, **kwargs):
+        ret = super(PatronictlPrettyTable, self)._stringify_hrule(*args, **kwargs)
+        where = args[1] if len(args) > 1 else kwargs.get('where')
+        if where == 'top_' and self.__table_header:
+            ret = self.__build_header(ret)
+            self.__hline_num += 1
+        return ret
+
     def _is_first_hline(self):
         return self.__hline_num == 0
 
@@ -71,8 +83,7 @@ class PatronictlPrettyTable(PrettyTable):
 
         # Inject nice table header
         if self._is_first_hline() and self.__table_header:
-            header = self.__table_header[:len(ret) - 2]
-            ret = "".join([ret[0], header, ret[1 + len(header):]])
+            ret = self.__build_header(ret)
 
         self.__hline_num += 1
         return ret

tests/test_ctl.py

@@ -7,10 +7,11 @@ from datetime import datetime, timedelta
 from mock import patch, Mock
 from patroni.ctl import ctl, store_config, load_config, output_members, get_dcs, parse_dcs, \
     get_all_members, get_any_member, get_cursor, query_member, configure, PatroniCtlException, apply_config_changes, \
-    format_config_for_editing, show_diff, invoke_editor, format_pg_version, CONFIG_FILE_PATH
+    format_config_for_editing, show_diff, invoke_editor, format_pg_version, CONFIG_FILE_PATH, PatronictlPrettyTable
 from patroni.dcs.etcd import AbstractEtcdClientWithFailover, Failover
 from patroni.psycopg import OperationalError
 from patroni.utils import tzutc
+from prettytable import PrettyTable, ALL
 from urllib3 import PoolManager
 
 from . import MockConnect, MockCursor, MockResponse, psycopg_connect
@@ -648,3 +649,24 @@ class TestCtl(unittest.TestCase):
             result = self.runner.invoke(ctl, ['reinit', 'alpha', 'other', '--wait'], input='y\ny')
         self.assertIn("Waiting for reinitialize to complete on: other", result.output)
         self.assertIn("Reinitialize is completed on: other", result.output)
+
+
+class TestPatronictlPrettyTable(unittest.TestCase):
+
+    def setUp(self):
+        self.pt = PatronictlPrettyTable(' header', ['foo', 'bar'], hrules=ALL)
+
+    def test__get_hline(self):
+        expected = '+-----+-----+'
+        self.pt._hrule = expected
+        self.assertEqual(self.pt._hrule, '+ header----+')
+        self.assertFalse(self.pt._is_first_hline())
+        self.assertEqual(self.pt._hrule, expected)
+
+    @patch.object(PrettyTable, '_stringify_hrule', Mock(return_value='+-----+-----+'))
+    def test__stringify_hrule(self):
+        self.assertEqual(self.pt._stringify_hrule((), 'top_'), '+ header----+')
+        self.assertFalse(self.pt._is_first_hline())
+
+    def test_output(self):
+        self.assertEqual(str(self.pt), '+ header----+\n| foo | bar |\n+-----+-----+')