Set role to uninitialized if data directory was removed in runtime

Fixes https://github.com/zalando/patroni/issues/542

patroni/ha.py

@@ -1014,6 +1014,7 @@ class Ha(object):
 
             # is data directory empty?
             if self.state_handler.data_directory_empty():
+                self.state_handler.set_role('uninitialized')
                 # In case datadir went away while we were master. TODO: check for this and try to stop postgresql.
                 self.watchdog.disable()
 

tests/test_ha.py

@@ -862,6 +862,7 @@ class TestHa(unittest.TestCase):
         self.ha.has_lock = true
         self.p.data_directory_empty = true
         self.assertEquals(self.ha.run_cycle(), 'released leader key voluntarily as data dir empty and currently leader')
+        self.assertEquals(self.p.role, 'uninitialized')
 
         # as has_lock is mocked out, we need to fake the leader key release
         self.ha.has_lock = false