Merge branch 'hv/remote-end-hung-up'

Merge branch 'hv/remote-end-hung-up'

When we get disconnected while expecting a response from the remote
side because authentication failed, we issued an error message "The
remote side hung up unexpectedly."

Give hint that it may be a permission problem in the message when we
can reasonably suspect it.

* hv/remote-end-hung-up:
  remove the impression of unexpectedness when access is denied