add -y for ssh test

tests/test_backup.py

@@ -19,7 +19,7 @@ def test_ssh(server):
 
 def test_last_backup_is_recent(server, client):
     path = '/backup/%s/current' % client
-    cmd = 'ssh %s ls -l %s | grep current' % (server, path)
+    cmd = 'ssh -y %s ls -l %s | grep current' % (server, path)
     status, out = subprocess.getstatusoutput(cmd)
     if status == 0:
         date = out.strip().split(' ')[-2]