SSL error during connection loss; OpenSSL.SSL.SysCallError (-1, 'Unexpected EOF')

• Gajim git master 06.06.2018
• python-nbxmpp 0.6.6

It is already not the first time I saw this (but I don't remember such errors with Gajim 0.16.x).

06/17/2018 23:53:40 (I) nbxmpp.transports_nb _do_receive, caught SSL error, got None:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/nbxmpp/tls_nb.py", line 172, in recv
    retval = self.sslobj.recv(bufsize)
  File "/usr/lib/python3/dist-packages/OpenSSL/SSL.py", line 1686, in recv
    self._raise_ssl_error(self._ssl, result)
  File "/usr/lib/python3/dist-packages/OpenSSL/SSL.py", line 1541, in _raise_ssl_error
    raise SysCallError(-1, "Unexpected EOF")
OpenSSL.SSL.SysCallError: (-1, 'Unexpected EOF')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/nbxmpp/transports_nb.py", line 616, in _do_receive
    received = self._recv(RECV_BUFSIZE)
  File "/usr/lib/python3/dist-packages/nbxmpp/tls_nb.py", line 180, in recv
    raise SSLWrapper.Error(self.sock or self.sslobj, e)
nbxmpp.tls_nb.SSLWrapper.Error: <class 'nbxmpp.tls_nb.SSLWrapper.Error'> for 146.255.57.229:5222: [Errno: -1] ((-1, 'Unexpected EOF')), Caused by <class 'OpenSSL.SSL.SysCallError'>((-1, 'Unexpected EOF'))
06/17/2018 23:53:40 (I) nbxmpp.transports_nb Disconnected by remote server: #-1, (-1, 'Unexpected EOF')
06/17/2018 23:53:40 (I) nbxmpp.client_nb Disconnecting NBClient: 
06/17/2018 23:53:40 (D) nbxmpp.client_nb Client disconnected..