♻️ Always go into logout state in #disconnect

If `disconnected?` returns true, the connection state is most likely
already `logout`.  But, just in case, we'll ensure it's set every time.

Author: nevans

lib/net/imap.rb

@@ -1116,8 +1116,8 @@ def tls_verified?; @tls_verified end
     #
     # Related: #logout, #logout!
     def disconnect
+      state_logout! unless connection_state.to_sym == :logout
       return if disconnected?
-      state_logout!
       begin
         begin
           # try to call SSL::SSLSocket#io.